A state by state look at key races and measures on the ballot on Tuesday. The number of electoral votes is in parenthesis.
Alabama (9) - Safe for Republican Mitt Romney.
Alaska (3) - Romney will win.
Arizona (11) - Romney's. GOP Rep. Jeff Flake in tougher-than-expected race for Senate against Democrat Richard Carmona.
Arkansas (6) - Romney territory. Republicans aim for open House seat held by Democrats.
California (55) - President Barack Obama gets the biggest state. Democratic Sen. Dianne Feinstein coasting. Democratic Reps. Brad Sherman and Howard Berman square off. Ballot measure would replace death penalty with life in prison and no parole.
Colorado (9) - Presidential battleground state. GOP Rep. Mike Coffman, backed by tea party, faces challenge. Ballot question legalizes marijuana for personal use by adults.
Connecticut (7) - Safely Obama's. Democratic Rep. Chris Murphy has slight advantage in close race with Linda McMahon for open Senate seat.
Delaware (3) - Obama's with ease. Democratic Sen. Thomas Carper and Gov. Jack Markell headed for new terms.
District of Columbia (3) - Obama's, overwhelmingly.
Florida (29) - Biggest presidential battleground, so hard fought that Dems go to court to extend early voting. Dem. Sen. Bill Nelson favored; tea party-backed Rep. Allen West struggles.
Georgia (16) - Part of Romney's Southern base. Republicans try to defeat Democratic Rep. John Barrow.
Hawaii (4) - Obama a winner in his native state. Democratic Rep. Mazie Hirono on her way to the Senate.
Idaho (4) - Safe as can be for Romney.
Illinois (20) - State that sent Obama to the Senate will vote for him again. Democrats target first-term Rep. Bobby Schilling and veteran Judy Biggert in new districts.
Indiana (11) - Safe for Romney, four years after Obama won it. Democratic Rep. Joe Donnelly holds late lead in polls over Richard Mourdock in costly Senate race. Republican Rep. Mike Pence favored for governor.
Iowa (6) - Presidential battleground. GOP Rep. Tom Latham favored over Democratic Rep. Leonard Boswell in redistricting struggle.
Kansas (6) - Reliably for Romney.
Kentucky (8) - Safe for Romney. Sen. Mitch McConnell not on the ballot, but GOP leader has a big stake in overall Senate battle. Republicans target Democratic Rep. Ben Chandler.
Louisiana (8) - Another southern state for Romney. GOP Reps. Charles Boustany and Jeff Landry face off.
Maine (4) - Obama favored for state, but Republicans talk of winning one electoral vote. Former Gov. Angus King, an independent, favored to win with Democrats' backing over both major party candidates.
Maryland (10) - Obama with ease. Democratic Sen. Ben Cardin coasting to re-election. Democrat John Delaney favored over GOP Rep. Roscoe Bartlett in redrawn district. Same-sex marriage measure on ballot.
Massachusetts (11) - Obama wins the state where Romney was governor. Republican Sen. Scott Brown faces very tough challenge from Elizabeth Warren in race that cost more than $65 million.
Michigan (16) - Despite late GOP ads, Obama favored in state that benefited most from auto bailout. Dem. Sen. Debbie Stabenow winning re-election.
Minnesota (10) - Lining up for Obama despite late Republican push. Democratic Sen. Amy Klobuchar safe for a second term.
Mississippi (6) - Romney will win easily, as will Republican Sen. Roger Wicker, seeking a new term.
Missouri (10) - Romney territory. Democratic Sen. Claire McCaskill favored over Rep. Todd Akin after his controversial remark about rape. Democratic Gov. Jay Dixon faces re-election challenge.
Montana (3) - A Western win for Romney. Bruising challenge for Democratic Sen. Jon Tester from Rep. Dennis Rehberg. Democrats hope to hold governor's office.
Nebraska (5) - Romney's with ease. Republican Deb Fischer, surprise winner of Senate primary, hopes to hold off late charge by former Sen. Bob Kerrey.
Nevada (6) - Obama has upper hand in long-time presidential battleground with large early vote. Appointed Republican Sen. Dean Heller narrow favorite for full term.
New Hampshire (4) - New England battleground, where Romney sets election eve rally. A pair of rematches in state's House seats, and open governor's office.
New Jersey (14) - Obama's, even before glowing praise from Republican Gov. Christie. Democratic Sen. Bob Menendez safe.
New Mexico (5) - Obama. Democratic Rep. Martin Heinrich narrowly favored to hold vacant Senate seat despite late push from former Rep. Heather Wilson.
New York (29) - Big for Obama. Sen. Kirsten Gillibrand coasting to new term. Dems target GOP Reps. Nan Hayworth, Ann Marie Buerkle and Chris Gibson after redistricting. Republicans go after Rep. Kathy Hochul.
North Carolina (15) - May be Romney's best battleground state, but Dems have big early voting lead and polls are close. Republican Pat McCrory favorite in governor's race.
North Dakota (3) - Safe for Romney. GOP Rep. Rick Berg slight favorite for open Democratic-held Senate seat. GOP Gov. Jack Dalrymple seems safe.
Ohio (18) - Late polls consistently show narrow advantage for Obama in battleground of battlegrounds. Sen. Sherrod Brown expected to survive $30 million ad onslaught from GOP groups.
Oklahoma (7) - Romney's easily. Republicans eye House seat left open by Democrat.
Oregon (7) - West Coast win for Obama.
Pennsylvania (20) - Should be Obama's, despite Romney campaign visit on Sunday. Polls show narrow advantage for Democratic Sen. Bob Casey.
Rhode Island (4) - Obama's with ease. Democratic Sen. Sheldon Whitehouse coasting to second term, but Rep. David Cicilline faces strong challenge.
South Carolina (9) - Romney will win easily in state where he lost presidential primary overwhelmingly.
South Dakota (3) - Republican state for Romney. Also for GOP Rep. Kristi Noem.
Tennessee (11) - Romney with ease. GOP Sen. Bob Corker, too. Tougher times for GOP Rep. Scott DesJarlais after revelations he once discussed abortion with mistress.
Texas (38) - Romney's biggest single-state prize. Ted Cruz will be a new Republican senator.
Utah (6) - Mormon votes could make this Romney's best state. Republicans Orrin Hatch in Senate, and Gary Herbert, governor, safe for new terms.
Vermont (3) - Obama territory. Independent Sen. Bernie Sanders coasting, and Dem. Gov. Peter Shumlin, too.
Virginia (13) - Battleground presidential state, with former independent Rep. Virgil Goode also on the ballot. Costly race between former Democratic Gov. Tim Kaine and former Sen. George Allen for Senate.
Washington (12) - Obama winning easily. So, too, Democratic Sen. Maria Cantwell. Very competitive governor's race.
West Virginia (5) - Romney by far. Sen. Joe Manchin and Gov. Earl Ray Tomblin, both Democrats, safe.
Wisconsin (10) - Battleground in White House race trending Obama's way. Democratic Rep. Tammy Baldwin and former GOP Gov. Tommy Thompson in close contest. GOP vice presidential candidate Paul Ryan safe for new House term - if he needs it.
Wyoming (3) - Romney's with ease. GOP Sen. John Barrasso coasting to new term.