Upvote:3
The closest thing I've found to a detailed history of this is here. It's not written by a professional historian, and it's a long and rather rambling essay. (It also was apparently written before the 2000 election, so it doesn't cover recent developments as discussed in the question.) But it basically does trace the history of the Electoral College in detail, including a lot of information on when states switched methods of selecting Electors.