Spanish settlers first used the borderlands for raising livestock, with missions receiving land grants from the king of Spain for ranches along the area north of the Rio Grande. Mounted herdsmen known as VAQUEROS tended cattle, horses, and burros as well as sheep, goats, and pigs. With the introduction of large-scale irrigation in 1898 and the arrival of the railroad in 1904, however, the once desert-like range of the Rio Grande Valley also became a prime location for agricultural production. Aided by the influx in MIGRANT WORKERS, commercial farmers cultivated established crops such as cotton and sorghum as well as introduced new ones, including vegetables and—most importantly—citrus fruit. Notwithstanding multiple freezes between the 1940s and 1980s, agribusiness remains a mainstay of the region’s economy and helps to make Texas one of the largest citrus producers in the country.