Both numbers are estimates and may change as officials count more absentee and provisional ballots.
McDonald suggested the turnout to be about equal to or better than 1964, but not higher than 1960 when John F. Kennedy squeaked out a victory over Richard Nixon. The turnout rate then was 63.8 percent.
The total voting in 2008 easily outdistanced 2004's 122.3 million, which had been the highest grand total of voters before.
Curtis Gans, director of the nonpartisan Committee for the Study of the American Electorate at American University and dean of turnout experts, estimated the total votes to be between 126.5 million and 129 million.
Different experts calculate turnout rates in different ways based on whom they consider eligible voters.
What's most interesting about early results is not just how many people voted but the shifting demographic of American voters, said Stephen Ansolabehere, a political science professor at Harvard and MIT.
Using exit polling data, Ansolabehere determined that whites made up 74 percent of the 2008 electorate. That's down considerably from 81 percent in 2000 because of increase in black and Hispanic voting, he said.
"That's a big shift in terms of demographic composition of the electorate," Ansolabehere said early Wednesday.
Breakdown by party voting also shows that Republican turnout rates are down quite a bit, while Democratic turnout rates are up, Gans said.
Republican states, such as Wyoming and South Dakota, saw turnout drop. "I think they were discouraged," Gans said.
Experts pointed to a weak economy and a lively campaign that promised a history-making result for the high turnout.
North Carolina set a record for its highest turnout rate of eligible voters, because of close presidential, Senate and gubernatorial races, Gans said. Other states where turnout increased were Indiana, Delaware, Virginia and Alabama. The District of Columbia also set a record, he said.
Ansolabehere said young voters didn't show up in the advertised wave, but others disagreed.
"Young voters have dispelled the notion of an apathetic generation and proved the pundits, reporters and political parties wrong by voting in record numbers today," said Heather Smith, the executive director of Rock the Vote. "The Millennial generation is making their mark on politics and shaping our future."
Wayne State University nursing student Audrey Glenn, 19, spent four hours waiting to cast her vote in Michigan, in part because Southfield election officials couldn't find her name on their lists.
"But it was all worth it," she said.
Ann Canales, a 47-year-old single mother, emerged from her Texas polling place with a wide grin, accompanied by her 16-year-old son.
"I've just been waiting for this day," said Canales, who voted for Barack Obama.
Norma Storms, a 78-year-old resident of Raytown, Mo., said her driveway was filled with cars left by voters who couldn't get into nearby parking lots.
"I have never seen anything like this in all my born days," she said. "I am just astounded."
In some places the wait lasted hours, and lines stretched for half a mile.
"Well, I think I feel somehow strong and energized to stand here even without food and water," said Alexandria, Va., resident Ahmed Bowling, facing a very long line. "What matters is to cast my vote."
Associated Press writer Ann Sanner contributed to this report.