SACRAMENTO -- One of the most closely contested presidential races in modern history fueled a record rise in voter registrations across California during the past two months, Secretary of State Kevin Shelley said Thursday as he announced that 16.5 million residents are registered for Tuesday's election.

Shelley predicted at least 12 million of them will vote, an estimated turnout of 73 percent.

The secretary of state reported that nearly 1 million Californians signed up to vote during September and October, driving registrations 1.5 million higher than the March 2 primary that helped nominate President Bush and Democratic Sen. John Kerry for Tuesday's showdown.

From tiny Sierra County in northern California to teeming Los Angeles County in the south, three-fourths of the state's 22 million voting-age residents are registered to vote on Tuesday, the highest percentage since 1996, when 80 percent of eligible California voters were registered.

Shelley cited "tremendous interest in this presidential election" for pushing California for the first time past the 16 million mark. The state's previous high was 15.7 million registrations during the 2000 presidential contest in which Democrat Al Gore carried California with 53.5 percent of the vote. Slightly more than 11 million Californians voted Nov. 7, 2000, a turnout of 71 percent.

About 70 percent of those eligible voted in last year's recall campaign that elected Gov. Arnold Schwarzenegger.

The state's surge in registrations is "in large part due to the presidential race and the intensity of feeling and the organizational effort that's gone into increasing" the number of voters," said University of California at Davis political science professor Edmond Costantini.

"There were a lot of lessons to learn from 2000," he added, "and one was boy, every vote can count."

Shelley reported absentee voting is also up sharply for Tuesday's election. He said California's 58 counties issued 4.3 million absentee ballots by the Oct. 26 deadline, 1.3 million more than four years ago.

Though polls show Kerry with a double-digit lead over Bush in California, Tuesday's election also features a U.S. Senate race between Republican former Secretary of State Bill Jones and Democratic Sen. Barbara Boxer, 53 U.S. House races, 100 legislative races and 16 ballot propositions ranging from stem cell research to reforming the state's 1994 "three-strikes" sentencing law. Hundreds more races will fill city councils, school boards and special districts.

Los Angeles County, with 4 million registered voters, has the state's highest total, adding 400,000 since March.

But numbers jumped in even the smallest counties.

Sierra County, population 3,500, reported that 91.4 percent of its eligible 2,600 voters are registered, the state's highest percentage.

"The last month we had a good surge of voter registration cards that came in," said assistant county clerk Heather Foster. "It was incredible."

The county has 22 voting precincts, but all residents vote by mail, Foster said.

California counties with the highest percentage of registered voters include El Dorado, San Luis Obispo, Humboldt, Tuolumne and San Francisco. Registrations in all range from 85 to 88 percent of eligible voters.

Among the least active, registering 64 to 69 percent of their eligible voters, are San Bernardino, Tulare, Yuba, Imperial and Kern counties.

Thursday's report showed Republicans dominating 37 counties and Democrats controlling 21, although in sheer numbers, Democrats continue to hold a 43 percent to 34.7 percent registration edge over Republicans. But statistics also showed Democrats' share of registration down from 45.3 percent in November 2000, while Republicans were down only slightly. New registrations also show that loyalty to political parties has declined 3 percent since 2000, while those registering as "decline to state" have jumped to nearly one in five voters.