First returns are expected in the next hour in what opinion polls indicate will be a close U.S. presidential race.
Voters are choosing between Republican incumbent George W. Bush and Democratic challenger John Kerry after a long and heated campaign focused on the war on terrorism, Iraq, and the economy.
U.S. election officials are reporting a heavy voter turnout.
The election will likely be decided in about 10 so-called "battleground" states, where Mr. Bush and Mr. Kerry are virtually tied, including Ohio, Florida, and Pennsylvania.
Voters also are choosing all 435 members of the House of Representatives, one-third of the Senate, 11 state governors and thousands of local officials.
Mr. Bush voted near his (Crawford) Texas ranch. He told reporters he feels calm and confident of victory.
After voting in his hometown, Boston (Massachusetts), Senator Kerry said he is confident he has "made the case for change."