Preliminary figures suggest fewer people voted this year than four years ago, when voters shattered turnout records as they elected Obama to his first term.

In most states, the numbers are shaping up to be even lower than in 2004, said Curtis Gans, director of American University's Center for the Study of the American Electorate. Every state is showing lower numbers than in 2008, Gans said. Still, the full picture may not be known for weeks because much of the counting takes place after Election Day.

"This is one of those rare elections in which turnout in every state in the nation went down," Gans said.

In Texas, turnout for the presidential race dropped almost 11 percent from 2008. Vermont and South Carolina saw declines that were almost as large. The drop-off was more than 7 percent in Maryland, where voters approved a ballot measure allowing gay marriage.