Founded as St. Clair about 3 miles east, Gladewater moved to its present site on Glade Creek and the T&P Railway in 1872. Its population grew from 500 to 7000 after oil was discovered in 1931, and it became a hub of production and refining operations. It also developed as a manufacturing, clothing, medical, farming, and dairy center. Gladewater is home to the annual East Texas Quarter Horse Show, and its Round-Up Association sponsors a nationally known June rodeo in a unique arena, an abandoned crude oil storage pit. Historic sites are marked, and the city has the world's richest self-supporting cemetery.