But despite some machine hiccups and delays, early voting appeared to go smoothly as an unprecedented 24 states held primaries and caucuses to nominate the Democratic and Republican nominees for president.
New Jersey Gov. Jon Corzine was supposed to cast his ballot in a Hoboken fire station, but both precinct machines weren't working.
Forty-five minutes later, after a repair person was called in, Corzine was able to vote. There was no word on what caused the delay.
Voters also waited in long lines in Illinois and Georgia.
Eight precincts in Chicago had minor problems and a ninth was expected to stay open for several extra hours after misplaced voting equipment caused a nearly two-hour delay in opening the polls.
At a Chicago hot dog joint doubling as a polling place, a technical glitch left only one touch-screen machine in use, making the line to vote much longer than the queue at U Lucky Dawg's counter, where the specials of the day included a Flying Mario Burrito for $3.09.
In Georgia, where voters are now required to present photo identification, wait times in some areas were as long as 90 minutes because for the first time in a major election, poll workers had to compare IDs against computerized registration records.
"That process with the computer terminals is very slow and that can create some long lines," said Clare Schexnyder of Election Protection, a national election monitoring group. "We're finally figuring out that it's not that there are not enough voting machines, it's the check-in process."
By its nature, electronic voting is prone to both man-made and technical glitches.
"Voting machines are always going to have issues. That's inevitable," said Tova Wang of The Century Foundation think tank. "They're machines that are operated by human beings. The question is whether the poll workers are trained and have everything they need. If the machines malfunction, do they have paper ballots and do they have enough of them?"
Weather was a concern in some cold-weather states. Snow or rain fell in Connecticut, Illinois, Kansas and Massachusetts, and elections officials worried that might discourage some voters. In Tennessee, where temperatures were forecast to reach the 70s, a storm front threatened to bring hail and tornadoes.
In the lead-up to Super Tuesday, voting advocates worried that long lines, high turnouts and record numbers of mail-in ballots in states such as California could drag out the counting process for days. Across the country, election officials have estimated that mail-in ballots may account for as much as 50 percent of the vote in some areas.
More than 5 million people have requested mail-in ballots in California, where there are 15.7 million registered voters. Election officials in the most populated and delegate-rich state in the country have said results may not be available until Wednesday or later.
As much as 25 percent of the overall vote may go uncounted Tuesday night, officials said. A major cause of expected delays is late-arriving mail-in ballots, which will be counted only after precinct votes are tallied. Polls close at 8 p.m. PST.
Another element is the state's recent switch from electronic voting machines to paper ballots. Four of California's most populous counties - Riverside, San Bernardino, San Diego and Santa Clara - must count votes at centralized locations because there aren't enough optical scanners for every precinct. Los Angeles and Sacramento will also haul their paper ballots to a single location, where they will be tallied electronically.
"We're working as late as we can to get all of them counted," said San Bernardino registrar Kathi Payne.
