Jackson acknowledges that no one knows how to plan the perfect community. And his belief that master-planning is still an evolving science is one reason he and the Centennial partners are eager to borrow what they consider the best ideas from cities around the country. When I asked Jackson how they settled on Centennial’s size, he explained that the first goal was a population large enough to achieve the critical mass needed for a self-sustaining community. Planners like Jackson use an array of sophisticated software programs, based on demographic and market research, that enable them to calculate the population and density required to animate new neighborhoods. Such programs also help them figure out how many schools and police stations they may need. To see their work as a real-life version of the computer game SimCity isn’t far off. “To have a grocery store you need 5,000 to 7,000 homes,” Jackson says. The 23,000 housing units planned for Centennial — a number that is likely to go down in the environmental review process — reflects the need to have enough residents for shopping centers, restaurants, movie theaters and business development, without making Centennial too congested. A city of 50,000 might also be large enough for a new branch of a university. Ultimately, Jackson’s plan envisioned Centennial as eight communities, each with a village center and multiple neighborhoods of about 50 homes each. In all, there would be about 1,000 acres of commercial and industrial property. The city would have a network of paseos and greenways to encourage biking and walking, and a variety of designs to conserve water and energy. Fifty percent of the town would be open space.

The much trickier part comes next: engineering a balanced society, mainly through the use of real estate prices. Centennial’s most notable difference compared with existing master-planned communities is that much of its housing, the developers are promising, will be within reach of working- and middle-class Californians. Whether it continues to be over time is a more unsettled matter; if Irvine and Columbia have diverged significantly from their original utopian impulses, it’s because they have skewed toward affluence as their populations and vitality have increased. “If you look at land values, Irvine is a great success,” says Michael H. Ebner, an urban historian at Lake Forest College in Illinois, who is writing a book about suburban America. Yet Irvine, as it has grown, has not been able to preserve the broad level of affordability its planners initially hoped for, Ebner says. In fact, its median household income — $83,000 — is well above the California median of $54,000.

Jackson and his colleagues created a model of what the ideal Centennial city population would be. They wanted diversity: old people and young families and singles; rich folks and working-class people, too. The Centennial partners envisioned a community that would include rental apartments and housing prices that would start at around $250,000. This is in large part a matter of practicality. Police officers, teachers and other essential building blocks of a community need to be able to afford to live where they work, especially if it’s in a remote city; new residents may also need financial incentives to be pioneers in a place where the concrete is barely dry. Moreover, in the Los Angeles region, where three-bedroom houses often start at $500,000, low prices could be a big draw. (The planners calculate that the lower-cost housing in Centennial would be affordable to more than 70 percent of California’s households.) So the initial phases of construction would focus on less-expensive housing and rentals, because those buyers and renters are the people Centennial needs to give it life. In a few years, after things have “snowballed,” as Jackson put it, those who arrived early would find opportunities to move up. In other words, by the time initial buyers and renters became higher earners, more-expensive neighborhoods would be going up in Centennial, some with million-dollar homes. Meanwhile, as older residents aged, there would be options for downsizing — into those original rental apartments, for instance, as well as small upscale homes or senior housing.

“It’s a very complex model between your needs of who you want to bring into the community and how that community matures over time,” Jackson said. “We’ll go back and revisit this every year for the next 25 years, and we’ll tweak it, because you never quite get it right.” Jackson mentioned that many things about the plan have already been tweaked, including the name. At first the proposed city was called Rolling Meadows, because that suited the site’s geography. Then the planners wanted a name that suggested a community that was both old and new. One day Robert Stine, a fan of the writer James A. Michener, suggested the title of Michener’s book “Centennial,” and everyone agreed. That sounded just about right.

Image Credit... Vincent Laforet for the New York Times

To Stine, developing Centennial is not just a matter of flipping a chunk of Tejon for a quick profit. “We’ve been here for 150 years, and the ranch is going to be here 150 years from now,” he says, “so I think anything we want to put our thumbprints on we want to be of a quality that’s going to enhance the value of the surrounding land and in no way detract from it.” Of course, none of these intentions preclude the future possibility, when Centennial is not just grasslands but a real city, that Tejon will in turn slice off and develop other pieces of land from its immense holdings. Then Centennial won’t be just a stand-alone city. It may be the hub of a new region. Stine does not necessarily rule this out.

Opponents of Centennial and Tejon Mountain Village have demanded that the ranch forswear just such a future, however. “Instead of piecemeal development, we’re looking for a ranch-wide plan, so that everyone acknowledges the larger picture,” says Ileene Anderson, a Los Angeles-based staff biologist for the Center for Biological Diversity, one of a dozen environmental groups that have formed a coalition to oppose the Tejon developments. “In the future,” Anderson told me, “are we going to be fighting multiple development issues in sensitive areas, well past my lifetime? The notion would be that since the developments are starting to roll out, let’s figure out where the best places for development are, as well as the best places for conservation. We’d like to see a comprehensive plan so that all of the cards are on the table.”