The Santa Gertrudis headquarters has functioned since the 1850s as the working nerve center of King Ranch, one of the largest ranches in the world at roughly 825,000 acres across South Texas. Founded by steamboat captain Richard King beginning in 1853, the ranch developed as a large-scale cattle and horse operation on the harsh South Texas brush country, pioneering ranching and land-management practices adapted to the region's climate. Its most notable agricultural achievement was the development of the Santa Gertrudis breed, created by crossing Brahman and Shorthorn cattle and officially recognized by the U.S. Department of Agriculture in 1940 as the first cattle breed developed in the United States. The ranch also built a significant horse-breeding program, raising both quarter horses and thoroughbreds, including Assault, winner of the 1946 Triple Crown. Beyond livestock, the King Ranch operation diversified over time into farming, oil and gas, and other agribusiness ventures, becoming one of the largest privately held corporations in the country. The Santa Gertrudis division remains an active, working ranch headquarters today, not a museum piece, and its historic core is recognized as a National Historic Landmark. Visitors can tour portions of the property through the King Ranch Visitor Center in Kingsville, which offers guided tours of the historic headquarters grounds, ranching exhibits, and access to the adjacent King Ranch Museum.