Pike, PA and Sussex, NJ are thanks to commuters, Pike is actually considered part of the NYC metropolitan area and I have heard of people commuting from Pennsylvania to NYC (though I suspect most commuters probably go to somewhere else in the NYC area.) Ozaukee, WI is obviously due to Milwaukee suburbia takeover, though if it flipped prior to that it could be the revolt against Democrats that happened in most heavily German areas after WWI. Carroll, MD is another obvious case of exurban takeover, from Baltimore.
Schoharie, NY is interesting though, I wonder what the story is there. There must've been some type of local machine, maybe a DA opted to finally put some party boss behind bars and the machine never really recovered.
Pike and Sussex didn't have NYC commuters back in the 1920s and 1930s. That's a far, far more recent phenomenon than their Republican voting patterns.
