I think it was 4 years ago (could have been another election) that I read a detailed article after that election how certain counties successfully swayed the election...how very few counties decided.
Been looking for it but can’t find it.
Not sure if this is it, but it highlights a book by Ed Morrissey (anti-Trumper) who did autopsy of the 2012 election and came up with 10 counties that swung the election in 2012...