Rialto is a city in San Bernardino CountyCaliforniaUnited States. According to Census Bureau estimates, the city had a total population of 93,284 in 2005. Rialto is home to four major regional distribution centersStaples, Inc., which serves stores across the entire West Coast of the United StatesToys “R” UsFedEx 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.