Rialto is a city in San Bernardino County, California, United States, 56 miles east of Los Angeles, near the Cajon Pass, Interstate 15, Interstate 10, State Route 210 and Metrolink routes. Its population was 104,026 as of the 2020 Census, up from 99,171 at the 2010 Census. Its population and economic activity have grown rapidly in recent years due to the building of major distribution centers in the region. The U.S. Army Rialto Ammunition Storage point was used during World War II to support operations in the Pacific theater. Rialto is home to major regional distribution centers: Staples Inc., which serves stores across the entire West Coast of the United States, Amazon, Under Armour, Medline Industries, Niagara Bottling, Monster Energy and Target in the northern region of the city, in the Las Colinas community. One of the United States' largest fireworks companies, Pyro Spectaculars, is also headquartered in Rialto.