Cities along what was known as the Citrus Belt began as fruit colonies centered on the growing and production of fruit. Citrus fruits were especially important to the growth and economy of the region, and Rialto was no exception. Citrus groves and packing house facilities stretched from San Bernardino to Pasadena. Rialto was an important part of the Orange Empire. Navel oranges were best suited to the climate and soil, and unlike wind-sheltered groves, the winds from Cajon Pass protected the crops from frost. At the peak of the citrus era, Rialto had seven packing houses and the citrus harvest was a year-round operation.