The 1920s also saw the startup in 1926 of the new DuPont plant at Belle, to make ammonia from coal using high-pressure synthesis.

The DuPont Belle Works was a key chemical plant for over 90 years. Built in 1925 in coal country, it used high-pressure machines called "hypers" to make ammonia and other chemicals. This helped create important products like nylon, which was used for parachutes and shoelaces during World War II, and Lucite, a clear plastic for airplane canopies.

The plant also made fertilizers that helped feed the growing world population. After the war, demand for its products increased, and it switched from coal to natural gas in 1959. The plant stopped making ammonia in 1978 and modernized over time, now employing fewer workers. In 2015, DuPont's chemical business became Chemours, which still operates at the site. The plant’s old equipment is gone, but its impact on 20th century American life remains important.