The question to ponder before results start coming in: How big will the House Republican victory be? Predictions range from 50 to 70 Republican pick-ups. Election Day morning, Intrade, a site set up like a stock market for political predictions, had Republican chances of winning the House at 97 percent.

The Rust Belt—Pennsylvania, Ohio, Indiana—is one part of the country to look to as a bellwether. These post-industrial districts likely will have some of the tightest races.

House Democrats who are in districts that voted for John McCain in 2008 are especially vulnerable. Rep. Kathy Dahlkemper, D-Pa., won in 2008 even though the district went for McCain—but she will likely lose this race to Republican Mike Kelly, a political newcomer who owns a car dealership. Dahlkemper was also one of the Stupak Democrats who voted for healthcare reform after initially protesting that it could provide federal funding for abortion. If Republicans don’t win the McCain districts, then the high expectations for the party have been inflated.

If Republicans can win independents across the country, the wave will be bigger than if they just regain McCain districts. Polls also have shown independents fleeing Democrats, and Ohio’s 15th district, which swings on independent voters, may prove whether polls reflect reality. Democratic Rep. Mary Jo Kilroy is trying to fend off a challenge from her 2008 opponent, Republican Steve Stivers, but she’s lagging in polls. The district went for President Obama in 2008 but backed President Bush in 2004.

House Republicans can go ahead and uncork the champagne if they win Democratic districts like Indiana’s 2nd. Democratic Rep. Joe Donnelly won reelection there in 2008 with two-thirds of the vote, but he faces stiff competition from Republican Jackie Walorski, a state representative. Donnelly was also one of the Stupak Democrats who ended up voting for healthcare reform. He’s still up a few points in polls and President Obama won his district by 9 points in 2008.

Another reason to watch the Rust Belt is because results will arrive early—earlier than those for tight races in Colorado and California, for example. Indiana’s polls close at 6 p.m., Ohio’s at 7:30 p.m., Pennsylvania’s at 8 p.m.

The presumptive next Speaker of the House, Republican leader John Boehner, will be watching the results in Washington.

To keep up with the results of these and other House races, go to WORLD’s home page and click on the U.S. House tab above the interactive national map.