At 10:00 p.m. Eastern next Tuesday, the nation will likely know who its next president will be.
The last battleground state–Nevada–is scheduled to close its polls at that time, but if current polling data is correct, Barack Obama will have sealed up the nomination by that point. If Nevada’s five electoral votes are to alter the outcome of the presidential race, John McCain will need to sweep Obama in all but one or two battleground states, depending which one(s).
But things won’t necessarily be decided by 10 p.m. The nation could wait hours before knowing who won if vote tallies stay close in tight battleground states, preventing major news organizations from calling those states.
Right now, polls indicate tight races (in or around the margin of error) in Florida, Indiana, Missouri, North Carolina, Georgia, and Montana. If those states are too close to call, up to 82 electoral votes could remain in question.
Another factor that could keep the nation guessing is legal action to keep polls open later than their scheduled closing times; an NAACP lawsuit against Virginia seeks to keep polls open late in that state, and lawsuits filed up until election night could keep polls open later elsewhere, especially if irregularities are reported.