Rancho San Pedro was one of the first California land grants and the first to win a patent from the United States. The land grant was validated by the Mexican government at 48,000 acres (190 km2) in 1828, and a United States patent validating 43,119 acres (174.50 km2) was issued in 1858. The original Spanish land grant included what today consists of the Pacific coast cities of Los Angeles harbor, San Pedro, the Palos Verdes peninsula, Torrance, Redondo Beach, Hermosa Beach, and Manhattan Beach, and east to the Los Angeles River, including the cities of Lomita, Gardena, Harbor City, Wilmington, Carson, Compton, and western portions of Long Beach and Paramount.
Juan José Domínguez (1736–1809), a Spanish soldier, arrived in San Diego, California, in 1769 with Fernando Rivera y Moncada and served with the Gaspar de Portolà expedition and, along with Junípero Serra, traveled to San Juan Capistrano, San Gabriel, and Monterey. In 1784, Dominguez was granted a concession of seventeen Spanish leagues, or 75,000 acres (300 km2), from the Spanish Empire.