In the confusion that followed the 2000 U.S. presidential election, President Clinton said "Never again will Americans be able to say 'My vote doesn't count.'" (Or something like that. I can't be bothered looking it up.) Anyway, the real message of that election was just the opposite. Thanks to the Supreme Court's decision (Bush v. Gore, 2000), ALL American's can say "My vote doesn't count." Or more precisely, my vote won't be counted.
But the real bottom line here is that close elections suck. For one thing, much as we'd like to think elections are a reasonably fair process, all the evidence of 2000 and later elections say it just ain't so. Registration can be questionable. Ballots are subject to overvotes and undervotes. Voting machines and counting machines can have serious defects. And that's not even considering the human aspects of the process.
There's a huge possibility of an election swinging one way or another based on chance. Bad weather affects elderly voters more than others. Exit polling and predictions have an effect on outcomes in later timezones. And jackbooted thugs kicking down doors of minority homes tends to limit voter turnout among those groups. In a close election, seemingly minor factors can have a huge effect.
So get your ass out there and vote tomorrow.
Unless you're a Republican.