A look at the congressional seats, governorships, state legislatures and some of the measures that will be on ballots Tuesday.
Thirty-seven Senate seats are up for election, 19 held by Democrats and 18 by Republicans. Fourteen of these seats are open — six Democratic and eight Republican — meaning there is no incumbent competing in the election.
Three of the races are open because the incumbent lost his or her primary election: Sens. Bob Bennett, R-Utah, Lisa Murkowski, R-Alaska, and Arlen Specter, D-Pa. Murkowski is running as a write-in candidate.
The party breakdown in the Senate is 57 Democrats, 41 Republicans and two independents who caucus with the Democrats.
All 435 House seats are at stake. A party must win 218 seats to get a majority.
The party breakdown in the House is 255 Democrats, 178 Republicans and two vacancies.
Four House incumbents lost their primary elections: Reps. Alan Mollohan, D-W.Va., Parker Griffith, R-Ala., Bob Inglis, R-S.C., and Carolyn Cheeks Kilpatrick, D-Mich.
Thirty-seven state governorships are up for election. Of these 19 are held by Democrats and 18 by Republicans. Twenty-four are open — 12 Democratic and 12 Republican.
Fifteen of the races are open because the incumbent is barred from running again by term limitations. One race is open because the incumbent, Gov. Jim Gibbons, R-Nev., lost his primary race.
The party breakdown on governorships is 26 Democrats and 24 Republicans.
A total of 6,115 out of 7,382 state legislative seats are up for election in 46 states.
Currently 27 state governments are controlled by Democrats and 14 by Republicans. Eight state governments are divided between the two parties. One state, Nebraska, has only a nonpartisan state senate.
One hundred sixty ballot questions will be decided in 37 states. Of these, 42 were initiated by citizens.
One of the most well-known ballot measures is the California initiative to legalize recreational use of marijuana. Three other states will also tackle this issue to different degrees. Arizona and South Dakota will both vote on the legalization of using marijuana for medical purposes. A measure in Oregon would establish a medical marijuana supply system and allow limited sales of marijuana.
In Colorado, the ballot will include a proposed amendment that would define a person in the state's bill of rights from the beginning of "biological development," potentially laying the framework for outlawing abortion in Colorado.
Arizona, Colorado and Oklahoma have proposed amendments aimed at taking down the segment of the new federal health care law that will require people to have health insurance.
Sources: The Associated Press, Senate press gallery, House press gallery, National Governors Association, National Conference of State Legislatures