Dexter is a city in Cowley County, Kansas, United States. As of the 2010 census, the city population was 278.
Early in the 20th century Dexter became the focus of research that would confirm the existence of an abundance of naturally occurring and readily available helium. In May 1903, a newly drilled natural gas well was found to contain a nonflammable gas. Researchers at the University of Kansas found the “Dexter gas” contained only 15 percent methane and 72 percent nitrogen, causing the gas to be nonflammable. In addition they discovered helium within an “inert residue” in the gas and, after expanding their research to other wells throughout Kansas, Missouri, and Oklahoma, published a paper in 1907 saying that helium could be extracted from natural gas. Helium did not have any practical applications at the time, but by 1917 the federal government was sponsoring extensive research into the possibility of using helium in airships.
Dexter is located at 37°10′46″N 96°42′58″W / 37.179373°N 96.715987°W / 37.179373; -96.715987 (37.179373, -96.715987). According to the United States Census Bureau, the city has a total area of 0.3 square miles (0.7 km2), all of it land.