According to Nate Silver's popular 538.com website, which aggregates all the latest election polls, North Carolina is the tightest state in the 2008 presidential race.

Silver's latest NC projection has Obama at 49.6% and McCain at 49.3% -- the razor-thin .3% difference making NC the most hotly contested state in the nation.

Missouri (49.5/48.7, advantage McCain) and Florida (49.6/48.6 Obama) are close behind.

Here's how the closest Southern states measure up in Facing South's latest Southern Swingability Rankings (TM):

SOUTHERN SWINGABILITY RANKINGS* as of 11/3

1 - North Carolina - Obama +.7
2 - Florida - Obama +1.9
3 - Georgia - McCain +3.7
4 - Virginia - Obama +5.5
5 - West Virginia - McCain +11.1

As many pundits point out, Obama may not need a Southern state to win the election if he can hold on in states like Colorado and Pennsylvania.

But the Obama campaign doesn't see it that way. Today, on the most important day of campaigning before election day, Obama will be stumping in Florida, North Carolina and Virginia.

UPDATE: The latest Public Policy Polling survey [pdf] -- not included in the above averages -- calls it a photo finish in North Carolina: Obama leads McCain by only one point, 50% to 49% in NC. PPP reports:
Barack Obama's chances in North Carolina on Tuesday really could depend on the weather. PPP projects that he racked up a lead of a little over 250,000 voters during early voting. He led 55-45 among those who said they had already voted in our poll, and a little over 2.5 million North Carolinians have already cast their ballots.
* The Institute's Swingability Rankings measure states by how close they are in the presidential race and therefore the degree to which they could "swing" either way. Rankings are based on the polling trend averages at Pollster.com, the state projections at 538.com, and a dash of secret sauce.