From preliminary election returns, it appears that these are the best counties for five particular presidential candidates:
Nader: Morgan County, Tennessee 5.2%
Barr: Esmeralda County, Nevada, 2.7%
Baldwin: Millard County, Utah, 5.6%
McKinney: either St. Bernard or LaFourche, both in Louisiana, each 1.1%
Brian Moore: Essex County, Vermont, 2.1%
Thanks to Jack Ross for doing the laborious job of checking all the counties; also thanks to David Leip of the US Election Atlas. Of course when the returns are final, these may change. For the major parties, McCain’s best county is King County, Texas, at 93.2%; Obama’s best jurisdiction is Washington, D.C., which gave him a higher percentage than any county in any state, 92.9%. Aside from D.C., Obama’s best county is Prince Georges County, Maryland, 89.1%.