Mammoth Spring State Park in Mammoth Spring, Arkansas, centers on Mammoth Spring, a National Natural Landmark whose water begins as rainfall in southern Missouri, travels underground, and emerges in Arkansas in immense volume. The spring powered local industry after an 1887 limestone dam created Spring Lake and supplied energy for mills and a cotton gin, and later supported a hydroelectric plant that operated from 1925 to 1972. Railroad history also shapes the site through a restored 1886 depot museum. Created from land taken for park use in 1957 and expanded through 1975, the park blends recreation with the industrial and transportation history of the surrounding community.