Richard King (1824-1885), a Rio Grande steamboat captain, bought two Spanish land grants on Santa Gertrudis Creek and founded the legendary King Ranch in 1853. He brought longhorn cattle from Mexico and battled droughts and cattle thieves to build a profitable ranch. Operating first in partnership with G. K. ("Legs") Lewis and later with Mifflin Kenedy and James Walworth, King became sole owner in the late 1860s. During the Civil War (1861-1865), the King Ranch was a way-station for Confederate cotton going to Mexico. Herds carrying King's famous "Running W" brand followed the cattle trails to northern markets in the 1870s.

After King died, his widow Henrietta (Chamberlain) (1832-1925) named as ranch manager Robert Justus Kleberg (1853-1932), who later married her daughter Alice Gertrudis King (1862-1944). The ranch became less isolated in the early 1900s, when the railroad arrived and the town of Kingsville was settled. Constant improvement of herds by King-Kleberg descendants produced a new breed of cattle, the Santa Gertrudis, and fine quarter horses and thoroughbreds. Petroleum was discovered on ranch property in the 1930s. Today the King ranch has grown to almost one million acres in south Texas, plus holdings in other states and nations.