 This business would be the largest lumber producer in the south, with Kirby controlling 300,000 acres (1200 km²) of timberland.At its peak between 1910 and 1920, it had some 16,500 employees and included twelve operating mills and five logging camps.The following year, and after the discovery of oil at Spindletop, Kirby partnered with Patrick Calhoun of the "Houston Oil Company" of Texas.