Formed from Bexar Territory, created February 1, 1858; recreated August 21, 1876; organized July 3, 1877. Named in Honor of James H. Callahan, 1812-1856 soldier in the Texas Revolution, captain of the Texas Rangers. County Seat, Callahan City, 1877; Belle Plain, 1877-1883; Baird, since two early military roads, the Chisholm Trail, and the first government telegraph line traversed this region.