The Vision Made Real: the Birth of Modern Diamond Bar

For Diamond Bar, 1956 was a year of destiny. The Capital Company, the acquisition arm of the Transamerica Corporation, purchased the Diamond Bar Ranch for $10 million from the Bartholome family with big plans.

The purchase included 8,000 acres of rolling ranch land with stands of oak, walnut and pepper trees shading riparian crossings in an unincorporated jurisdiction, and the visionary new owners made plans to replace the cattle with people.

Transamerica and Diamond Bar were to make history together as they pioneered a new concept in land use: the master-planned community.

The sheer size of acquired open land allowed for extensive pre-planning of amenities that would enable the marketing of a community offering a bucolic lifestyle.

Taking up the history of the ranch, the Diamond Bar cattle brand — a diamond bisected by a bar — became the logo and "Country Living" became the unofficial motto.

“It was the 1950s,” long-time community activist John Forbing said in explaining why strip malls and small shopping centers still speckle thoroughfares.

"The husband would drive the only family car to work," Forbing said. "The wives walked to the grocery stores, and the kids rode bikes everywhere."

For years, Forbing said, a large sign where Kmart and Ace Hardware now do business proclaimed, "Future Site of Diamond Bar High School."

In the early years of Diamond Bar, everyone’s mail "was delivered to The Diamond Bar Water Company office," Forbing said. "It was a little white building where now stands."

As executive director of the water company, the town’s second resident, Carlton J. Peterson, became the de facto postmaster as “residents picked up their mail there,” Forbing said.

By the time the walls of the first homes went up, there were still no freeways through Diamond Bar. 

However, Presenting Diamond Bar, Volume II — the original master plan for the community of Diamond Bar — projected an optimistic five year timeline for the acquisition of the right of ways for the 57 and 60 freeways to connect Diamond Bar to the rest of the southland.

At the time, Brea Canyon Road provided the only access to Orange County.

Presenting Diamond Bar is replete with optimistic statements marketing the community’s future in the region:

The strategic location of Diamond Bar is such that these freeways provide direct access to important recreational areas without the necessity of passing through the contested traffic areas near the Los Angeles center of the freeway system.

Plans for roads within the community were much different as well.

Then, Pathfinder Road was not intended to dead end where it crosses Diamond Bar Boulevard.

Early maps show Pathfinder continuing as a major arterial road providing access to Chino by bending to connect to Grand Avenue at the top of the hill.

Don Ury, a long-time resident of Diamond Bar who oversaw development of the Country Estates as a Transamerica Vice President explained the decision as a change in preference.

"Taste in housing changed," Ury said. "The houses and lots got bigger."

With the development of The Country Estates, the major arterial connecting Diamond Bar to Chino was re-routed on Los Angeles and San Bernardino County maps with the extension of Grand Avenue replacing a connection via Pathfinder.

Presenting Diamond Bar also predicted a symbiotic relationship between Diamond Bar and the city of Industry. Planners anticipated that concurrent expansion of these neighboring cities was a logical pairing.

Diamond Bar, as a bedroom community, would provide the work force for jobs provided in the city of Industry.

But not all of the initial plans were to increase Diamond Bar's housing density.

Along Grand Avenue, which did not then connect with Chino, planners didn't set out to plant high-rise condominiums or apartments, but trees.