LOS ANGELES, California (CNN) -- People hoping to stay awake long enough Tuesday to see who won California's primary might have a long night.

Returns from California's primary could be delayed because of paper ballots.

Polls close in California at 8 p.m. PT, 11 p.m. on the East Coast. Even those who think they might awaken Wednesday to see results of the Democratic primary might still be waiting.

California is the biggest prize of the 24 states holding primaries and caucuses on Super Tuesday.

At stake: 370 Democratic delegates and 170 Republican delegates. Watch why California is so important »

Those numbers could make or break the contests between Arizona Sen. John McCain, former Massachusetts Gov. Mitt Romney, and former Arkansas Gov. Mike Huckabee on the Republican side, as well as Sens.Barack Obama of Illinois and Hillary Clinton of New York in the Democratic contest.

County registrars throughout California are warning that because of what could be record-breaking voter turnout and a change back to paper ballots, Tuesday's results may take some time.

Meanwhile, millions of California absentee ballots and early voting ballots are still out. Officials say many of those voters are expected to drop the ballots off at their polling places Tuesday.

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Because of concerns over reliability, California decertified many of the state's electronic voting machines. That means in places like San Bernardino County, east of Los Angeles, where more than 3,000 voting machines will be sitting in a warehouse, paper ballots are back.

Kari Verjil, a registrar with San Bernardino County, says paper ballots will require more time to tally the votes.

More than a third of the state's 58 counties will go from directly recorded electronic machines back to paper.

Los Angeles County never stopped using paper ballots, but poll workers still spent time this past weekend on a dry run, getting ready for the expected high volume of ballots.

More than 700,000 more Californians are registered to vote Tuesday than were four years ago; 240,000 signed up in December.

That jump in registered voters may be due, in part, to California officials moving up the state's primaries from June to Super Tuesday this year.

"All signs are that this is going to be a very high-turnout election," said Dean Logan, a registrar in Los Angeles County. "There is a lot of interest and a lot of activity. ... We know that California is at play in the presidential nomination process." E-mail to a friend

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