The Amarillo Helium Plant

Helium is an element that is found in natural gas. In the early 1900s, the US military tried to increase the nation’s supply of helium. Why? Helium can be an incredibly useful element.

• Helium is lightweight.
• Helium can conduct heat.
• Helium stays in gas form at very cold temperatures.
• Helium gas can move through solid materials since the molecule is so small.
• Helium does not react with other elements easily.

Until the early 1900s, though, helium was very rare. In the early 1900s, scientists learned how to isolate helium. They stripped it from natural gas. In the 1910s, engineers began to think about new uses for helium.

Current events of the day shaped their ideas. Between 1914 and 1918, World War I raged across the globe. Competition for rare natural resources was a major cause of the war. Tapping a new resource like helium could give the nation a military edge.

During World War I, the US Navy realized that helium could make airships float, since the gas is lighter than air. World War II led to more advancements in helium airships. Over time, the military and private industries learned about a wide variety of uses for helium – as described in the section on the National Defense and the Aerospace Industry.

Development of the Amarillo Helium Plant

As the need for helium grew, the American government looked to produce more. The U.S. Bureau of Mines took the lead in building helium plants. The Bureau of Mines led research on all types of minerals. This included natural gas, which included helium atoms. The helium atoms could be separated from the rest of the natural gas. All helium plants needed to be close to a source of natural gas. Texas held a supply of natural gas underground. As a result, many of the earliest helium plants were built in Texas. In 1915, the Bureau of Mines built the Petrolia Helium Plant near Wichita Falls. This was because the largest known supply of natural gas was in the nearby Petrolia Natural Gas Field. The Bureau of Mines also built two helium plants in Fort Worth in 1918. Natural gas flowed to Fort Worth through pipelines from Petrolia. The natural gas quickly ran out near Petrolia, though. By 1927, the Bureau of Mines began searching for new supplies of natural gas. They found a large supply at the Cliffside Natural Gas Field. Cliffside sat about 20 miles northwest of Amarillo, Texas. The Bureau of Mines then began planning a new helium plant in Amarillo. They also wanted to build a new helium research facility on the same property.

An early step in planning was to choose a site for the new plant. Many factors influenced their choice.

• The site needed access to natural gas.
• Railroads needed to be close by for shipping.
• Highways close by would help shipping, too.
• A big site without other buildings nearby was better for safety.
• A town needed to be close enough for workers to commute daily.

In 1928, the Bureau of Mines found the right site. It was located about eight miles west of downtown Amarillo, Texas. The Rock Island Railroad connected to the site. So did Route 66. Construction of the new plant began later in 1928. By 1929, the new Amarillo Helium Plant was ready to open. The volume of helium produced at the Amarillo plant quickly grew. By about 1934, the Amarillo Helium Plant was the only commercial helium plant in the world.

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Site plan showing the construction of new buildings over time at the Amarillo Helium Plant (Credit: Library of Congress)

In the 1940s, World War II created new demands for helium. The research labs discovered ways to refine more helium. They also learned how to make higher-quality helium. The Bureau of Mines constructed new buildings at the Amarillo Helium Plant to help with the process. In 1943, they also constructed the Exell Helium Plant about 35 miles to the north.

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Description of helium finances, around 1967. (Credit: U.S. Department of the Interior)

After World War II, demand for helium slowly declined. The Bureau of Mines stockpiled more helium than it sold. Some people also thought that private industries should make helium instead of the government. In the 1950s and 1960s, the Bureau of Mines began making the helium plant operate like a business. The Amarillo Helium Plant had to pay for its expenses with profits from the helium sold.

As funding declined, staff had to be laid off. By 1970, the Amarillo Helium Plant stopped making helium. A few remaining employees worked in the lab. Other employees still worked in administrative roles supporting the Exell plant. In 1996, a new law halted all federal funding for helium operations. The Amarillo Helium Plant closed its doors two years later, in 1998.

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Depiction of the evolution of uses at the Amarillo Helium Plant. (Credit: Carol Freeman and Kay Sallee)

Research

Universities began researching helium in the early 1900s. Researchers helped the US government understand uses for helium. They hoped helium would be useful for defense and flight. They also hoped to learn how to better extract and refine helium. Goals for research at the Amarillo Helium Plant included: 

• Increase the efficiency of helium processing 
• Make helium processing cheaper
• Increase the amount of helium produced
• Improve the purity of processed helium

The team of researchers in Amarillo succeeded. They increased efficiency and reduced the price of helium by 1933. Having plenty of helium allowed the US to fly blimps in World War II. By 1949, the team also increased the quantity and purity of helium by using ultra-cold temperatures to separate helium from impurities. The study of ultra-cold temperatures is known as “cryogenics.” These discoveries in cryogenics helped fuel jets and rockets. They even helped spacecraft keep pressure level in outer space.

Learn More! Listen to this 1998 oral history with former NASA employee Guy Thibodaux, explaining how helium was used to propel rockets.

Dr. Clifford W. Seibel

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Dr. Clifford W. Seibel in 1948 (Credit: The Petroleum Engineer magazine)

The lead researcher at the Amarillo Helium Plant was Dr. Clifford W. Seibel. He was born in Kansas City, Missouri in 1890. As a graduate student, Seibel helped pioneer extracting helium from natural gas. Seibel finished his PhD in 1915. After that, the US Bureau of Mines approached him. They hoped helium could help fill lighter-than-air blimps for World War I. Seibel began working for the Bureau of Mines in 1917. Early in his career, he worked at the Fort Worth Helium Plant. There, he demonstrated that helium could be purified using charcoal filters. In 1929, he helped design the Amarillo Helium Plant. Seibel continued to work at the Amarillo plant until retiring in 1958. During his career, he also researched using ultra-cold temperatures to purify helium. His lifelong work earned him the nickname “Mr. Helium.”

Applications of Helium

New research found many uses for helium. Most uses involved aircraft or space flight. Other types of uses involved medicine and meteorology.

Working at the Amarillo Helium Plant

The Amarillo Helium Plant employed more and more people between 1929 and 1968. Jobs at the local helium plant helped Amarillo’s economy grow. Other helium facilities in the area added to this trend. For example, the nearby Cliffside Natural Gas Field provided new jobs, and the Exell Helium Plant added even more when it opened in 1943. The city of Amarillo grew as a result. Amarillo became more important as a regional commercial hub. New houses, schools, and fire stations sprung up. A former employee at the Amarillo Helium Plant named C. F. David described the growth in an interview in 1998:

Then all of a sudden it became known that we were going to have a new high school when they knew that the plant was coming in. The federal government made certain stipulations . . . for the plant to be built there. We had to have paved streets. We had to have more houses. We had to have a new high school. We had to have a fire truck. The city changed completely.

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Employees outside the Administration Building, likely in the 1950s (Credit: Bureau of Land Management Archives)

New jobs at the helium plant also changed the character of Amarillo. Before the helium plant opened in 1930, most jobs in Amarillo related to farming or ranching. Some jobs also related to oil and natural gas, which were discovered nearby between 1918 and 1921. The helium plant brought more technical and professional jobs. Scientists and engineers moved to Amarillo from across the nation. Some employees brought new cultures and religions to Amarillo. The population became more diverse. Women also found jobs at the plant. Working together to create helium helped build community. Many employees remember their work at the Amarillo Helium Plant with a sense of pride.

The complex helium process required many different types of jobs. Jobs at the helium plant ranged from technical professions to manual labor. Some examples of jobs at the Amarillo Helium Plant are listed and illustrated below.

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Learn More! One known draftsman was named Charles Colarelli. Colarelli demonstrates the cultural diversity that the plant brought to Amarillo. Census records suggest that Colarelli was born in Colorado around 1938 to an Italian-immigrant gold miner. He moved to Amarillo to work at the helium plant around 1957. In 1940, the census showed about 10 Italian Americans living in Amarillo. Jobs at the helium plant helped the Italian community and other immigrant communities grow.

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Contributions of Women and Minorities

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A stillman at work, around 1980. Stillman operated the still -- the machine that separated helium from other elements. Stillmen rotated shifts so that someone was on duty 24 hours per day. This was necessary because it was difficult to stop the flow of helium through the pipeline, and backed-up helium in the pipeline could be dangerous. (Credit: TxDOT)

From the 1930s through the 1950s, most jobs at the Amarillo Helium Plant went to white men. The same was true for most government jobs across the nation at the time. Yet the plant also hired women and minorities for some important jobs. During World War II, most young men went overseas to fight. Labor shortages led the government and industry to seek more diverse workers. The US government encouraged hiring workers deemed physically “unfit” for military service. A government document recommended different jobs for people with different abilities. It cited the helium plant as a source of many types of jobs for people with physical disabilities. Types of jobs listed included engineers, mechanics, stillmen, foremen, superintendents, and laborers. Dr. Clifford Seibel wrote about their contributions in his 1968 book, Helium: Child of the Sun:

When difficulties arose in getting special copper pipe bends, handicapped men classified 4-F [“unfit for military service”] were trained to do the work in our own plant yard. Unwilling to trust the assembly of the separation equipment to unfamiliar hands, U. G. Hester, a helium plant foreman with many years of experience, collected a crew and took over that assignment with phenomenal success. Under his close supervision the Exell plant came through a test period with flying colors. This same fine service was also provided for the three additional wartime plants.

Learn More! Read about the contributions of individuals with physical disabilities during World War II in “4-F: The Forgotten Unfit of the American Military” by Tiffany Leigh Smith, from Texas Woman’s University.

In many places, women also helped meet wartime labor needs. The original design for the Amarillo Helium Plant included women’s locker rooms, just in case women were hired. However, no documents show women actually working at the Amarillo Helium Plant during World War II. Nearby, though, Amarillo Foundry hired women during World War II. These women helped build low-temperature equipment for the Amarillo Helium Plant. Dr. Clifford Seibel praised these women in his 1968 book:

When some eastern fabricators of copper equipment were “too busy to be bothered,” I turned in desperation to a superbly equipped local machine shop. With technical know-how and supervision from our own small force, Lowell Stapf--and his Amarillo Machine Shop and Foundry crews, augmented by some 30 women substituting for experienced drill press and light machine operators produced three-quarters of a million dollars’ worth of low-temperature equipment equal or superior to the best ever obtained from any source.

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Women at the Amarillo plant in the 1980s (Credit: TxDOT)

By the 1950s, women began working at the Amarillo Helium Plant. At first, most women worked in administration. The first documented woman employee was a mail clerk hired around 1951. Photos of the administrative offices at the plant from the 1950s also show a number of women. At least one additional woman, named Elizabeth Tucker, worked at the plant’s downtown office in the 1950s. Tucker was a trained stenographer who worked for the soil conservation office prior to the helium plant. Although married, Tucker is not documented as having children, which would have made it more socially acceptable for her to work in an era where social expectations often confined women to the home.

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The accounting office at the plant, likely around 1955 (Credit: U.S. Department of the Interior)

Women also gradually gained jobs outside the administrative office. Oral histories note women in various roles. These include two women working on the shipping docks, a woman draftsman, and several women in a library at the plant. Amarillo City Directories from the 1950s and 1960s list a few women working at the plant. They include Mrs. Beulah I. Carter and Mrs. Louise B. Stewart. Carter worked as a “caretaker” at the plant around 1960, and Stewart worked as a technician around 1960. Both had grown children, giving them the ability to work outside the home in an era with limited childcare.

The first woman scientist at the Amarillo Helium Plant, a chemist named Beverly Dalton Briggs, arrived in 1961. Briggs went on to supervise the U.S. Army’s efforts to remove landmines. When she died in 2001, her obituary noted her humanitarian efforts.

A woman mathematician named Marilyn Johnson came to the Amarillo Helium Plant in 1966. Johnson brought early understanding of computers to the plant. In the late 1960s and early 1970s, Johnson gained trust and authority. She gained access to all parts of the plant, including the Cliffside Natural Gas Field. She eventually rose to the position of “Programmer Analyst” and introduced the “Fortran” computer program at the plant. Johnson noted that the Amarillo plant was more accepting of women than other workplaces at the time.

Over the years, women in the administrative office also received promotions. By the 1970s, women held positions as accountants and purchasing agents. By the 1980s, women held administrative roles at all levels.

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Researchers in a lab at the plant, 1950. (Credit: National Archives)

The 1960s, 1970s, and 1980s also brought some limited racial and ethnic diversity to the plant. Two Chinese American chemists arrived at the plant in the 1960s. According to oral histories, these men were father and son. Although their first names are not known, their last names are remembered as “Chang.” A Mexican American petroleum engineer named Antonio “Tony” Salazar came to the plant in the 1970s. By the 1980s Salazar rose to the position of Head of Resources at the plant. Salazar also was active in the Amarillo community, volunteering as a youth sports coach and serving as president of the Amarillo Catholic School Board. An African American chemist also reportedly was hired in the 1980s, although his name also remains undocumented. A Mexican American petroleum engineer came to the plant in the 1980s as well, though his name also is lost to history.

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Learn More! Did you know that one of the leading helium researchers today is African American? Learn more about physicist Walter E. Massey from Brown University.

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Employee Life

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Draftsmen typically worked alongside engineers in the lab buildings or in the Engineering Building (Credit: Region VI: Helium Plants Book II)

For many employees, the helium plant formed the core of their community. Some employees even lived in the government housing “camp” at the nearby Exell Helium Plant. The Exell housing camp opened in 1942 with 75 houses and garages. The camp continued to house Excell and Amarillo employees until around 1978. The Amarillo employees took a bus from the Exell camp to the Amarillo plant each day. The Exell camp included a school and sports facilities, so the children of many helium employees grew up together. During the holiday season, Amarillo and Exell camp families held a joint gathering where a Santa handed out toys for the children. Other plant employees lived in private housing in Amarillo. During World War II, buses and flatbed trucks fitted with seats would transport some workers to the plant from a garage on West 6th Street in downtown Amarillo. As Dr. Seibel described in his 1968 book:

The transportation of workmen to and from Amarillo…was a problem. With tires and gasoline rationed, workmen required assurance of the necessary transportation before signing for work. Fortunately, our priority rating was high enough to obtain two 72-passenger semitrailer buses and tractor trucks to haul them.

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Employees in the control room monitored the equipment to keep the plant running safely and efficiently. Factors that needed to be controlled included gas flow, temperatures, and pressures (Credit: TxDOT)

Employees also organized sports for recreation at the plant. The plant originally included tennis courts. Employees at the plant also created a softball team around the 1950s. Other nearby helium plants also had their own team, as did the downtown Amarillo office, and the teams would play one another. The Bivens Helium Plant, located about 35 miles west of Amarillo, managed a golf course for the employees free of charge. Amarillo employees helped the Bivens employees maintain it. Employees from the Amarillo Helium Plant also formed bowling teams in the 1960s and 1970s.

Employees at the Amarillo Helium Plant also held other social gatherings and celebrations. Informal “get-togethers” in the Recreation Hall often included potluck meals with spouses and children. Outdoor picnics were another form of community gathering for employees. Overall, a sense of pride characterized life at the helium plant. Dr. Seibel expressed this feeling in an interview with the Amarillo Globe Times when he retired in 1959, stating: 

I couldn’t leave without doing a lot of bragging about the organization – its loyalty, sustained competence, imaginative thinking and the ability to put that thinking into practice. There’s not a group in the government that can touch them. The public, government and industry can be very proud of them.

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The Amarillo Helium Plant with a summary of its production process (Credit: Library of Congress)

The main purpose of the Amarillo Helium Plant was to extract helium from natural gas). Helium then needed to be purified. To purify the helium, the plant filtered out other molecules like carbon dioxide. Next, helium was compressed and stored in metal cylinders. Cylinders of helium then were shipped for storage or distribution using trains or trucks. The design for the plant kept all these purposes in mind. The U.S. Navy began designing the plant in 1928. The U.S. Bureau of Mines worked with the Navy to make sure that the design met the plant’s needs.

Relationship between Helium and the Natural Gas Industry

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The Cliffside Natural Gas Field in 1967 (Credit: TxDOT)

Helium occurs very rarely in nature. Some types of natural gas actually contain helium atoms, though. Scientists can separate these helium atoms from other molecules in natural gas. The Bureau of Mines knew that helium plants needed a source of helium-containing natural gas nearby. The site selected for the Amarillo Helium Plant was only about six miles south of the Cliffside Natural Gas Field . A pipeline connected the Amarillo Helium Plant to the Cliffside Natural Gas Field.

Helium Separation Process

Separating helium from natural gas formed the core of the plant’s purpose. Early separation techniques used charcoal filters. After 1939, the process for purifying helium changed. The plant began cooling the gas at very low temperatures. This made elements other than helium condense and liquify. Temperatures needed to get as low as minus 300 degrees Fahrenheit. Helium remained a gas even at this very low temperature.

Specialized buildings and equipment at the plant supported this new process. First, the pipeline brought the natural gas to a specialized building. Between 1930 and 1942, the helium first went to the “CO2 Removal Building” (shaded yellow on the 1929 site plan below). After 1942, a “Pump House” with more advanced equipment replaced the CO2 Removal Building in this process. (The Pump House site is shaded in purple) Equipment in these buildings stripped away carbon dioxide, water, and heavy molecules that solidified. Next, the natural gas flowed into the “Separation Building” (shaded blue). Equipment in the Separation Building included dryers, heat exchangers, and charcoal filters. The goal was reaching “Grade A” purity. To reach Grade A, the gas needed to contain 99.995% helium. Purified Grade A helium then was packaged for shipment.

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Original plan for the Amarillo Helium Plant, 1928. Highlights indicate the CO2 Removal Building (shaded yellow, used from 1930–1942), the future site of the 1942 Pump House (shaded purple), the Separation Building (shaded blue), the Power House (shaded orange), and the High Pressure Storage Building (shaded green). (Credit: TxDOT)

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The 1942 Pump House and equipment to remove carbon dioxide (Credit: National Archives)

The point of the separation process was to yield pure helium. Purification was very important for safety. Any carbon left in the helium could catch fire and explode.

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The Amarillo Helium Plant Power House in 1952. (Credit: National Archives)

The leftover natural gas could be used for power, and in fact, some of the natural gas powered the Amarillo Helium Plant. The complex had its own generator to turn leftover natural gas into electricity. The generator was located in the “Power House.” The plant sold surplus natural gas to nearby private gas companies.

Helium Compression

Once extracted, purified Grade A helium had to be compressed. Compressing the gas helped separate off any leftover nitrogen. Compression also helped make the helium compact for efficient storage and shipping. The compression equipment was in the Power House, along with the generators. Equipment included two nitrogen compressors and two helium pumps. The nitrogen compressors were manufactured by the Cooper-Bessemer Corporation of Vernon, Ohio. The helium pumps came from Worthington Industries in Columbus, Ohio. Worthington Industries also manufactured special, high-pressure metal storage cylinders. Large cylinders could measure 40 feet long. Small cylinders stood about 4 feet tall. Each small cylinder could hold about 200 cubic feet of helium. How did they squeeze such a large amount of gas into the tanks? The helium compressor applied 2,000 pounds of pressure per square inch to compact the gas.

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Compression cylinders in the Power House. (Credit: U.S. Department of the Interior)

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Nitrogen compressors and helium compressors in the Power House, 1952. (Credit: National Archives)

Helium Storage

The cylinders also made storing the helium convenient. Empty small cylinders were kept in the “Cylinder Storage Area” next to the CO2 Removal Building. Large empty cylinders waited in outside storage yards. Filled cylinders of helium were stored in the “High Pressure Storage Building.” The interior of the building featured special racks to hold the cylinders. This building also connected to loading docks to streamline distribution. Most helium storage took place away from Amarillo, though. The nearby Cliffside Field held a huge underground storage area. Having a supply of helium in reserve helped the US military stay prepared. Compressed helium could travel to the Cliffside storage area in cylinders or through a pipeline.

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Empty containers in the Cylinder Storage Area (right foreground) and outdoor cylinder yards (left background), 1953 (Credit: National Archives)

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Helium cylinders awaiting shipment (Credit: National Park Service)

Distribution

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Helium cylinders traveling on conveyor belts to loading docks at the Amarillo Helium Plant, 1989 (Credit: TxDOT)

Military bases and industries around the US relied on helium. Railroads and highways connected the helium plant to these consumers. Beginning in World War II, the Amarillo plant became the distribution hub for helium in the United States. The pipeline from the Cliffside storage area supplied most of the helium for distribution. The flow of helium through the pipeline was challenging to stop. This created demand for an efficient distribution system, which is reflected in the design of the Amarillo plant. Before 1949, most shipments of helium from Amarillo traveled on trains. The original site plan for the plant placed loading docks near rail lines. Trains used special tank cars designed to hold the heavy weight of the helium cylinders. After 1949, more trucks began carrying helium. Trucking companies designed special tanks to hold the helium. The flowchart below shows how the plant changed to respond. As the flowchart shows, new buildings were added at the south of the plant. These new buildings included loading docks and storage warehouses. In 1956, the old railroad tracks on the west and southwest sides of the plant were removed. The railroad tracks on the south side of the plant remained. This allowed both trains and trucks to use the new loading docks on the south side of the plant.

Route 66 and the Amarillo Helium Plant

The Amarillo Helium Plant was located on US Highway 66, or “Route 66.” When Route 66 opened in 1926, it became the shortest route from the Midwest to the Pacific Coast. The plant originally used trains to transport helium across the country, but it switched to trucks as highways developed.

Until the early 1900s, ships, trains, and wagons carried people and goods. Industrial plants often opened next to railroad lines or ports. In the late 1800s and early 1900s, fossil fuel production improved. At the same time, explorers across the world searched for new oil and gas. As new fuels became more available, so did machines that used them, such as trains and automobiles.

When deciding where to locate their new helium plant, the Bureau of Mines looked for a place that had easy access to road networks and helium supplies. The Amarillo location had many advantages. The property was very close to Cliffside Field, an abundant helium reserve. A system of gas pipelines provided a constant natural gas supply from Cliffside and other fields to plants in the Southwest. The Amarillo location was also near Route 66 and the Rock Island Railroad. This meant that helium coming from Cliffside connected Amarillo to other helium plants, military bases, and other locations throughout the country.

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The “Helium Conservation System Pipeline” extending through plants in Texas, Oklahoma, and Kansas. The Amarillo Helium Plant is shown just south of Route 66, in the lower left corner of the map. Note how all helium plants are near highways. (Credit: U.S. Department of the Interior)

The helium industry created specialized tanks to move the gas safely and easily. Special tank cars carried helium on trains, and semitrailers with massive tanks carried it on highways. These incredible tank vehicles could carry more helium at a lower weight.

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Helium is stored in special tanks for transportation. (Credit: U.S. Department of the Interior; “Helium, A Place in the Sun,” Welding Design and Fabrication, January 1968, reprinted as a courtesy of the United States Steel Corp.)

As cars and trucks gained popularity, new highway networks sprang up around the nation. Advanced transportation networks also helped the US military. Highways could help the military easily transport supplies and troops. Many states, including Texas, first established highway departments in 1917 to help with World War I. The 1917 plan for highways in Texas called for construction of State Highway 13, connecting Amarillo with Oklahoma. State Highway 13 was expanded and became Route 66 in 1926. This roadway was used to transport military troops and supplies during World War II. In 1954, President Eisenhower established the Interstate Highway System. One reason for establishing the system was to be more prepared for any future wars. Since the military used a great deal of helium, highways were especially important to the helium plant.

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Rail and highway routes connecting Amarillo to the rest of the country (Credit: Library of Congress)

Highways shaped the helium industry in many ways. At first, railroads ran to loading docks at the helium plant. But by 1947, trucks were more popular, and the loading docks expanded and improved. A 1962 report from the Bureau of Mines explained that trucks were beneficial because they could make “rapid trips over relatively short distances.” Helium shipments in semitrailers increased throughout the 1960s thanks to highways like Route 66.

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The loading dock at the Amarillo Helium Plant, showing a covered outside area for filling helium tanks for transportation (Credit: U.S. Department of the Interior)

The Purpose and Need for Helium

• “Daryl Leachman oral history interview conducted by the Bureau of Land Management, Amarillo, Texas, 1998.” From TxDOT archives, File 09_13_2000 - Daryl Leachman - 1A#C04B, 1B#ED0F, 2A#B8B1, and 2B#95F5.
• Freeman, Carol, and Kay Sallee. “A Cultural Landscape Inventory – Phase I – Bureau of Land Management Properties: Amarillo Helium Plant, Exell Helium Plant, and the Landis Property.” Prepared for the US Bureau of Land Management, May 1999. From TxDOT archives.
• Kleiner, Diana J. “Helium Production.” Handbook of Texas Online. Accessed February 26, 2021. https://www.tshaonline.org/handbook/entries/helium-production.   
• Peyton, Paige, PhD. “Amarillo Helium Plant Historic District.” National Register of Historic Places Inventory/Nomination Form. Texas Historical Commission, Austin. Draft dated July 14, 2019.
• “US Bureau of Mines, Helium Plants, Amarillo Helium Plant, 10001 Interchange 552, Amarillo, Potter County, TX.” Historic American Engineering Record. Washington, D.C.: National Park Service, US Department of the Interior, Documentation compiled after 1968. From Prints and Photographs Division, Library of Congress (HAER TX-105-A), https://www.loc.gov/item/tx0974/.
• US Department of the Interior, Bureau of Mines, Helium Activity. “Annual Report: FY 1967.” No publisher, 1967. From TxDOT archives. 

National Defense and the Aerospace Industry

• “Amarillo Helium Plant Information Gathering Form: Marilyn Johnson completed by Cox McLain Environmental Consulting, Amarillo, Texas, 2019.” From TxDOT archives.
• “Dale Bippus oral history interview conducted by the Bureau of Land Management, Amarillo, Texas, 1998.” From TxDOT archives. File 09_18_2000 - Dale Bippus - 1A#FD37.
• “Guy Thibodaux oral history interview conducted by the Bureau of Land Management, Amarillo, Texas, 1998.” From TxDOT archives, File 09_08_2000 - Guy Thibodaux#2AAA.
• Helium Centennial: Committee from Government and Industry. “Helium Fact Sheet” [Press Release]. No publisher, no date. From TxDOT research archives.
• “In what ways is helium used on modern launch vehicles?” SpaceExplorationBeta. Accessed April 7, 2021. https://space.stackexchange.com/questions/46112/in-what-ways-is-helium-u....
• Kleiner, Diana J. “Helium Production.” Handbook of Texas Online. Accessed February 26, 2021. https://www.tshaonline.org/handbook/entries/helium-production.   
• Lakey, Sherrel J. “B-29 Super Fortress” [photo]. 1944. From the Library of Congress, Control No. 2017868670, https://www.loc.gov/item/2017868670/.
• NASA. nasa.gov. Various documents.
• Peyton, Paige, PhD. “Amarillo Helium Plant Historic District.” National Register of Historic Places Inventory/Nomination Form. Texas Historical Commission, Austin, submitted July 14, 2019.
• TxDOT Time Capsule Event, Amarillo, 2018. Various scanned documents.
• “US Bureau of Mines, Helium Plants, Amarillo Helium Plant, 10001 Interchange 552, Amarillo, Potter County, TX.” Historic American Engineering Record. Washington, D.C.: National Park Service, US Department of the Interior, Documentation compiled after 1968. From Prints and Photographs Division, Library of Congress (HAER TX-105-A), https://www.loc.gov/item/tx0974/.
• US Department of the Interior, Bureau of Mines, Helium Activity. “Annual Report: 1960.” No publisher, 1960. From TxDOT archives. 
• US Department of the Interior, Bureau of Mines, Helium Activity. “Annual Report: FY 1967.” No publisher, 1967. From TxDOT archives. 
• US Department of the Interior Bureau of Mines. “Region VI: Helium Plants Book II. No publisher, no date. From the TxDOT Time Capsule Event, Amarillo, 2018, File MULT.TCE.DOC.1950s0000.Book II.pdf.

Employee Work and Life

• “Kids, Inc. Korner.” Amarillo Globe Times, May 23, 1973.
• “Meet...Vivian Salazar, Reporter.” Amarillo Globe Times, April 2, 1973.
• “Salazar Heads Amarillo Board.” Amarillo Globe Times, May 12, 1976.
• “Amarillo Helium Plant Information Gathering Form: Marilyn Johnson, completed by Cox McLain Environmental Consulting, Amarillo, Texas, 2019.” From TxDOT archives.
• Anderson, H. Allen. “Exell Helium Plant.” Handbook of Texas Online. Accessed April 13, 2021. https://www.tshaonline.org/handbook/entries/exell-helium-plant.
• “Beverly Dalton Briggs.” Find A Grave. Accessed April 15, 2021. https://www.findagrave.com/memorial/81484286/beverly-briggs.
• “Beverly Dalton Briggs” [obituary]. The Washington Post, May 2, 2001. https://www.washingtonpost.com/archive/local/2001/05/02/obituaries/8a5bf....
• Census records. Various Years. From ancestry.com.
• City Directories. Various Years. From ancestry.com.
• “CF David oral history interview conducted by the Bureau of Land Management, Amarillo, Texas, 1998.” From TxDOT archives, File 09_17_2000 - CF David - A#3DC5, transcript.
• “Dale Bippus oral history interview conducted by the Bureau of Land Management, Amarillo, Texas, 1998.” From TxDOT archives, File 09_18_2000 - Dale Bippus - 1A#FD37.
• “Daryl Leachman oral history interview conducted by the Bureau of Land Management, Amarillo, Texas, 1998.” From TxDOT archives, File 09_13_2000 - Daryl Leachman - 1A#C04B, 1B#ED0F, 2A#B8B1, and 2B#95F5.
• “Dave Cornelius oral history interview conducted by the Bureau of Land Management, Amarillo, Texas, 1998.” From TxDOT archives, File 09_18_2000 - Dave Cornelius - 2A#C222.
• “Harold Rhodes oral history interview conducted by the Bureau of Land Management, Amarillo, Texas, 1998.” From TxDOT archives, File 09_17_2000 - Harold Rhodes - 1A#1DF7.
• Historic Sites Atlas. Various records. From the Texas Historical Commission, https://atlas.thc.state.tx.us/.
• “Jim Vines oral history interview conducted by the Bureau of Land Management, Amarillo, Texas, 1998.” From TxDOT archives, File 09_19_2000 - Jim Vines.
• “John Litchfield oral history interview conducted by the Bureau of Land Management, Amarillo, Texas, 1998.” From TxDOT archives, File 09_14_2000 - John Litchfield - B#5791.
• Kleiner, Diana J. “Helium Production.” Handbook of Texas Online. Accessed February 26, 2021. https://www.tshaonline.org/handbook/entries/helium-production.   
• National Park Service, Santa Fe. “An Inventory of the Buildings at the Amarillo and Exell Helium Plants, Texas.” 1999.
• “Norma J. Snyder oral history interview conducted by the Bureau of Land Management, Amarillo, Texas, 1998.” From TxDOT archives, File 09_14_2000 - Norma J Snyder#5020.
• Seibel, Clifford W. Helium: Child of the Sun. Lawrence: The University Press of Kansas, 1968.
• Smith, Tiffany Leigh. “4-F: The Forgotten Unfit of the American Military.” Master’s thesis, Texas Woman’s University, 2013. From Texas Woman’s University, https://twu-ir.tdl.org/bitstream/handle/11274/325/2013SmithTiffanyOCR.pd....
• US Civil Service Commission Medical Division. “A Guide for the Placement of the Physically Handicapped” [annual serial]. Washington, D.C.: US Government Printing Office, 1949. From Google Books, https://play.google.com/store/books/details?id=cyKmUWKEdUwC&rdid=book-cy....
• “US Bureau of Mines, Helium Plants, Exell Helium Plant, Highway 287N, Masterson, Moore County, TX.” Site development drawing. Historic American Engineering Record. Washington, D.C.: National Park Service, US Department of the Interior, Documentation compiled after 1968. From Prints and Photographs Division, Library of Congress (HAER TX-105-B), https://www.loc.gov/resource/hhh.tx0975.sheet/?sp=3&st=single.
• US Department of the Interior, Bureau of Mines. “Region VI: Helium Plants Book II. No publisher, no date. From the TxDOT Time Capsule Event, Amarillo, 2018, File MULT.TCE.DOC.1950s0000.Book II.pdf.
• US Public Records Collection. Various records. From familysearch.org. 

Helium Production Process and Technology

• Anderson, H. Allen. “Amarillo, TX.” Handbook of Texas Online. Accessed June 17, 2021. https://www.tshaonline.org/handbook/entries/amarillo-tx.  
• “CF David oral history interview conducted by the Bureau of Land Management, Amarillo, Texas, 1998.” From TxDOT archives, File 09_17_2000 - CF David - A#3DC5.
• Freeman, Carol, and Kay Sallee. “A Cultural Landscape Inventory – Phase I – Bureau of Land Management Properties: Amarillo Helium Plant, Exell Helium Plant, and the Landis Property.” Prepared for the US Bureau of Land Management, May 1999. From TxDOT archives.
• Helium Centennial: Committee from Government and Industry. “Helium Fact Sheet” [Press Release]. No publisher, no date. From TxDOT archives, Amarillo Helium Plant Event at Helium Monument Time Capsule Reveal Collection, File No. MULT.TCE.DOC.19680000.DSC_0439-0458.
• Kleiner, Diana J. “Helium Production.” Handbook of Texas Online. Accessed February 26, 2021. https://www.tshaonline.org/handbook/entries/helium-production.   
• National Archives and Records Administration, College Park, Maryland. Various records.
• National Park Service. “An Inventory of the Buildings at the Amarillo and Exell Helium Plants, Texas.” Washington, D.C.: National Park Service, 1999. Reproduced in Peyton, “Amarillo Helium Plant Historic District.”
• Peyton, Paige, PhD. “Amarillo Helium Plant Historic District.” National Register of Historic Places Inventory/Nomination Form. Texas Historical Commission, Austin, submitted July 14, 2019.
• “US Bureau of Mines, Helium Plants, Amarillo Helium Plant, 10001 Interchange 552, Amarillo, Potter County, TX.” Historic American Engineering Record. Washington, D.C.: National Park Service, US Department of the Interior, Documentation compiled after 1968. From Prints and Photographs Division, Library of Congress (HAER TX-105-A), https://www.loc.gov/item/tx0974/.
• US Department of the Interior, Bureau of Mines, Helium Activity. “Annual Report: 1960.” No publisher, 1960. From TxDOT archives. 
• US Department of the Interior, Bureau of Mines, Helium Activity. “Annual Report: FY 1967.” No publisher, 1967. From TxDOT archives. 
• US Department of the Interior, Bureau of Mines. Various records. From TxDOT archives.