Guess the previous county's location and demographics based on it's voting history

[Schiff for Senate]

1980: Reagan + 9
1984: Reagan + 29
1988: Bush + 9
1992: Bush + 4
1996: Clinton + 7
2000: Bush + 7
2004: Bush + 15
2008: McCain + 9
2012: Romney + 8
2016: Trump + 33
2020: Trump + 30

It’s giving like Rural Montana

No offense meant but how do you figure a county in rural MT swings leftward in 2012?

[Schiff for Senate]

1980: Carter + 9
1984: Mondale + 5
1988: Dukakis + 19
1992: Clinton + 17
1996: Clinton + 4
2000: Bush + 18
2004: Bush + 27
2008: McCain + 47
2012: Romney + 54
2016: Trump + 62
2020: Trump + 64

Central Arkansas

85% Non-Hispanic White Alone
10% Non-Hispanic Black Alone
5% Other

Don't want to be nitpicky but I don't think it'd be in AR since most counties in rural AR trended harder to the right in 2020.

[Schiff for Senate]

1980: Reagan + 28
1984: Reagan + 36
1988: Bush + 22
1992: Bush + 5
1996: Dole + 11
2000: Bush + 18
2004: Bush + 12
2008: Obama + 3
2012: Romney + 6
2016: Trump + 3
2020: Biden + 5

I'm guessing a county in the Upper-Midwest with a population that's about 90% white, that was previously rural but is either in the exurbs of a major city or has a growing small city of its own.

And for the next county:

1960: Kennedy +34.3
1964: Johnson +45.4
1968: Humphrey +23.8
1972: Nixon +8.4
1976: Carter +20.7
1980: Reagan +0.1
1984: Reagan +0.4
1988: Dukakis +29.1
1992: Clinton +27.7
1996: Clinton +24.1
2000: Bush +6.2
2004: Bush +18.1
2008: McCain +8.0
2012: Romney +37.2
2016: Trump +44.5
2020: Trump +45.9

Would've been so much cooler had Carter in '80 and Mondale had won it, but any guesses?

It sounds like somewhere in Coal Country that is over 95% white and less than 20% have bachelor's degree or higher. My county was Leelanau, MI.

Would agree, expect the 2008 swing doesn't add up...most counties in coal county actually swung pretty hard rightward in 2008, not leftward.

[Schiff for Senate]

1980: Reagan + 15
1984: Reagan + 31
1988: Bush + 13
1992: Clinton + 5
1996: Clinton + 11
2000: Gore + 1
2004: Kerry + 2
2008: Obama + 19
2012: Obama + 9
2016: Trump + 4
2020: Trump + 3

Midwestern but semi-suburban (if it were rural I'd expect a larger rightward shift).

[Schiff for Senate]

1980: Reagan + 15
1984: Reagan + 31
1988: Bush + 13
1992: Clinton + 5
1996: Clinton + 11
2000: Gore + 1
2004: Kerry + 2
2008: Obama + 19
2012: Obama + 9
2016: Trump + 4
2020: Trump + 3

Midwestern but semi-suburban (if it were rural I'd expect a larger rightward shift).

That was Isabella, MI

1980: Reagan + 7
1984: Reagan + 31
1988: Bush + 11
1992: Bush  + 7
1996: Clinton + 5
2000: Bush + 9
2004: Bush + 14
2008: McCain + 0.1
2012: Romney + 2
2016: Trump + 7
2020: Trump + < 0.1

I'm going to say either a rural area in New England, or a semi-suburban part of NY. Pretty white either way.

Fictional, but it'd be interesting to see the input:

2020: Trump+6
2016: Trump+5
2012: Romney+8
2008: McCain+13
2004: Bush+17
2000: Bush+20
1996: Dole+9
1992: Bush+14
1988: Bush+30
1984: Reagan+40
1980: Reagan+33
1976: Ford+17
1972: Nixon+55
1968: Nixon+32 (over Humphrey; he was about 60 points ahead of Wallace)
1964: Johnson+3
1960: Nixon+12