Security Guard in Diamond Bar, CA

In 1840, José de la Luz Linares received the 4,340-acre (1,760 ha) Mexican land grant Rancho Los Nogales (Ranch of the Walnut Trees) from Governor Juan Alvarado. The land grant included Brea Canyon and the eastern Walnut Valley. Linares died in 1847, and his widow sold a part of the ranch to Ricardo Vejar for $100 in merchandise, 100 calves, and the assumption of her late husband’s debts. Vejar also owned the Rancho San Jose to the east, and acquired the rest of Rancho Nogales over the next 10 years.

However, Vejar’s luck did not last that long. As time wore on – and particularly as the United States government took over California – Rancho Los Nogales was divided and sold into multiple land ranches, the largest of which was the Diamond Bar Ranch. At the time, it was one of the largest working cattle ranches in the western U.S. The entire Diamond Bar Ranch was acquired by the Transamerica Corporation in the 1950s for the purpose of developing one of the nation’s first master-planned communities. Transamerica gave the Diamond Bar name to its new community and incorporated the ranch’s familiar diamond and bar cattle brand into various logos (many of which are still in use today).

The first houses in this development were built in 1959, adjacent to the future location of the Pomona Freeway, which was built through the area ten years later. The town’s development and population grew extremely quickly after that.