At the end of 2009, nearly 45 percent of the county’s residents spoke a language other than English at home, according to county officials. Whites now make up only 45 percent of the population; this county is teeming with Hispanics, as well as Vietnamese, Korean and Chinese families. Its percentage of foreign-born residents jumped to 30 percent in 2008 from 6 percent in 1970, and visits to some of its corners can feel like a trip to a foreign land.

Image Credit... The New York Times

The demographic changes that have swept the county reflect what is happening across the state and much of the nation. It has happened slowly but surely over the course of a generation, becoming increasingly apparent not only in a drive through the 34 cities that fill this sprawling 789-square-mile county south of Los Angeles, but also, most recently, in the results of a presidential election. In 2008, Barack Obama drew 48 percent of the vote here against Senator John McCain of Arizona. (By comparison, in 1980, Jimmy Carter received just 23 percent against Ronald Reagan, the conservative hero whose election as California governor in 1966 and 1970 was boosted in no small part by the affection for him here.)

“I was a city planner in San Diego in 1960 when Orange County was just orange groves and typecast as a conservative stronghold,” said Marshall Kaplan, the executive director of the Merage Foundations, which runs educational and other programs for recent immigrants here. “It isn’t anymore. I live in Irvine. My wife is Asian. In Irvine, I sometimes feel like I’m her affirmative action program.”

Manuel Gomez, the vice chancellor of student affairs at the University of California, Irvine, said the county where he was born 63 years ago is almost unrecognizable to him today. “With diversity comes more cultural voices and political voices,” he said. “And certainly better food.”

Orange County is not unique in being a reliable Republican region in California. But this county has always boasted of a zesty political brand: almost defiantly conservative, the anti-Los Angeles, a land of gated communities and great wealth that managed to produce a steady stream of colorful conservative figures, including the televangelist Robert H. Schuller and former Representative Robert K. Dornan  B-1 Bob, as he was known, for his advocacy of military projects. (In a sign of what was to come, Mr. Dornan lost the House seat in 1996 to a Democratic Latina, Loretta Sanchez).