Whether they want to vote for America's next president – or are eager to feel generally more enfranchised – immigrants in California's Central Valley became U.S. citizens at an explosive rate in 2007, according to an analysis of new naturalization statistics.

The Valley's cities are far smaller than San Diego or Los Angeles, which also experienced surges in the thousands of people becoming citizens in 2007. The Los Angeles area alone saw 78,454 new citizens sworn in last year – a 19 percent increase over the year before.

But the rate of growth in naturalizations in the Central Valley in just one year is startling for the inland region – and it helped fuel a 19 percent jump in new citizens throughout California last year.

The failure of immigration reform in Congress, the pending presidential election, a citizenship drive by Latino civil rights groups – and the desire to get applications in before a fee hike in August 2007 could all explain last year's increases, said Sharon Rummery, spokeswoman for U.S. Citizenship and Immigration Services.

At the southern end of the Central Valley, the Bakersfield area saw the number of new citizens rise from 1,357 in 2006 to 2,576 in 2007 – a leap of 90 percent, according to a Bee analysis of the most recent naturalization data available from USCIS, a branch of the U.S. Department of Homeland Security.

Bakersfield's jump in naturalizations was the biggest percentage increase of any metropolitan region in the United States.

El Paso, Texas, was second, with an 87 percent increase.

Back in California, the Central Valley city of Modesto ranked third, with a 73 percent increase. Fresno was fourth, with 69 percent, followed by Stockton, with 50 percent more new U.S. citizens.

Sacramento, the Central Valley's most populous metropolitan region, ranked 11th in the nation for increases. The metropolitan area saw 40 percent more new citizens sworn in in 2007 – 8,974 – compared with 6,428 in 2006.

Figures showing the native countries of those naturalized in 2007 are not yet available. But in 2006, about 25 percent of new citizens were born in Mexico, about 10.5 percent were born in the Philippines and 10 percent in China and Taiwan combined.

At an April swearing-in ceremony in Sacramento, 42 percent of the 1,900 new citizens were from Mexico.

Irma Martinez took her oath on June 27, 2007.

Raised in a village in Jalisco state, Mexico, the 50-year-old Sacramento woman said she has never voted before in her life, and she wants to cast a ballot in November for president.

"We must elect our own lawmakers," said the factory worker.

She became a legal U.S. resident after a 1986 federal amnesty. Her husband became a citizen 13 years ago, she said, but for years she was too afraid that she'd make mistakes in her English and fail the test.

Pro-naturalization activists who visited Martinez's church urged her to take citizenship classes to overcome her fear. She also said she became angry at politicians and others blaming illegal immigrants for abusing health care services and for causing problems.

"One comes here to work," she said, "not cause problems."

Monica Willemsen, 30, who was born in Guatemala, came to the United States as a teenager and has since earned a master's degree in architecture. She also was naturalized last year in Sacramento.

Like Martinez, she said she was motivated to become a citizen because she's concerned about hostility toward immigrants.

Willemsen also is concerned that the American ideals she cherishes are not being practiced abroad, and she wants to have a voice in changing that. She is campaigning for Democratic Party presidential candidate Barack Obama.

Hans Johnson, a demographer with the Public Policy Institute of California, said last year's citizenship increases remind him of a similar surge in the late 1990s. Mexican immigrants in particular became U.S. citizens in greater numbers during the emotional aftermath of Proposition 187, the 1994 measure that would have required all children in California's public schools and people receiving non-emergency health care to prove they were legal residents.

The proposition was struck down as unconstitutional.

"But one of the long-lasting consequences of Prop. 187," Johnson said, "was it mobilized substantial numbers of Latinos to become citizens and register to vote, and they did so mostly as Democrats."

He said that California – and other parts of the Southwest – have a "large pool" of legal immigrants of Mexican origin who are eligible to become U.S. residents.

One of the messages during mass immigrant protests in 2006, Johnson said, was 'Get involved – vote.' "

Officials with USCIS say they expect the citizenship wave to roll on for some time, at least through 2008.

In the wake of the 2006 protests, the Spanish-language television network Univision, labor unions and Latino civil rights groups formed a citizenship coalition called "Ya es Hora," or "It is Time."

The national coalition organizes immigrants, persuading them to go to classes and helping them fill out citizenship applications.

USCIS reported receiving more than 1.4 million citizenship applications in 2007, nearly double the number received in 2006.

The Sacramento office received 25,518 citizenship applications in 2007 from people in northeastern California, from San Joaquin County north and east. The office naturalized 17,474 people that year.

Between January and July of this year, the Sacramento office received 5,645 applications and completed 12,148 naturalizations.

Call The Bee's Susan Ferriss, (916) 321-1267.