No. 36 Killam Family
277,000 acres (up 22,000 acres)
In 1920, O.W. Killam abandoned a promising career in Oklahoma politics to move his family to Laredo, Texas, in hopes of striking oil. Although his first attempts met with failure, the third time proved the charm. Today, David Killam serves as the managing partner of Killam Companies; Cliffe Killam runs Killam Oil, which operates nearly 300 wells.