In 1956, Diamond Bar Ranch looked much as it did in 1840, with its golden hills peppered by green stands of oak and walnut trees, and grazed by large herds of cattle. Transamerica Corporation, which purchased 8,000 acres of Brea Canyon, soon mapped out a master-planned community that, today, has become home to more than 56,000 residents.

Incorporated in 1989, the City of Diamond Bar embraces a progressive approach to promoting and assisting business enterprises. Well suited for many types of business, Diamond Bar is conveniently located at the center of three major Southern California market areas; Los Angeles, Orange, and San Bernardino counties.