Which state will be the closest state?

[Torrain]

History suggests that several states will have a margin under 1%, and the closest state often comes out of left field (see 2016), with a margin under 0.5%.

I'd say there are three options. If Biden is having a bad night, I'd say it's likely to be NH. If he's winning an Obama 2012-style victory it'll be somewhere like GA or AZ. If its a blowout, I'd say somewhere like SC, AK or MT.

I've included a list of the closest states in presidential elections going back to Carter, for reference:

2016 - Michigan, 0.23%
2012 - Florida, 0.88%
2008 - Missouri 0.13%
2004 - Wisconsin 0.38%
2000 - Florida, 0.0092%
1996 - Kentucky, 0.96%
1992 - Georgia – 0.59%
1988 - Washington, 1.59%
1984 - Minnesota, 0.18%
1980 - Massachusetts, 0.15% 
1976 - Oregon, 0.16%