The Helium Beneath Kansas

Southwestern Kansas sits atop the Hugoton Natural Gas Field, one of the largest natural gas fields in the world, which also happens to contain the world's largest known reserves of helium. The United States government recognized the strategic value of helium so early that it passed the Helium Act of 1925 making helium a federally controlled resource. Helium is critical for MRI machines, fiber optic cables, semiconductor manufacturing, and rocket fuel systems, making Kansas's helium reserves quietly significant on a global scale.

Source: Wikipedia