Those states probably have a much higher educational attainment level, civic engagement/consciousness and intelligence level than the rest of the United States.

They did not have to contend with having to vie for the vote of 300+ million people.

Also, elections for governor do not have to account for the Electoral College which IMO is an anarchic holdover from a time when communication was much harder.

Maine is one of the few states where that's viable - as Nate Silver notes[1], it's probably the most independent-leaning state in the nation, as evidenced by its support for Ross Perot in the 90s. Rhode Island would be another, and I'd peg Colorado as a distant third.

Minnesota is an outlier in my mind - it's more attributable to the fact that the Republican candidate (Norm Coleman) was a terrible candidate (he only won his Senate seat because his opponent died right before the election[2]), and the race was irregular in other ways too. It happened once, but I wouldn't bet on it happening again there anytime soon, unless things change.

[1] http://fivethirtyeight.blogs.nytimes.com/2012/10/15/in-maine...

[2] To Coleman's credit, John Ashcroft ran against a dead man and lost, so I guess Coleman had something going for him.

> John Ashcroft ran against a dead man and lost

He lost to the dead man's wife, who the voters knew would take that seat even if the ballots couldn't be reprinted in time.