Shoshone County, ID in 1976

[they don't love you like i love you]

Here's a pretty strange electoral anomaly. Shoshone is an old mining county in northern Idaho that used to be a strength of unions and a Democratic enclave. It voted Democratic in every election from 1932 to 1948, voted for Eisenhower both times narrowly and well more Democratic than the national popular vote, voted D from 1960 to 1968, voted for Nixon in the 1972 landslide but still notably more D than the national numbers. Basically a textbook Lean D county.

Yet in 1976...
Ford (R) 51.67%
Carter (D) 46.55%

This is the only election between 1932 and 1996 where it voted more Republican than the national popular vote. It voted for Reagan both times, but somewhat weakly, in fact in 1984's Reagan's performance was fairly anemic and actually worse than Ford's, (50.22%-48.27%) and then it gave Dukakis over 60%. 1976 really stands out and makes no sense in the context of the rest of the results.

What happened then?

[maclennanc2]

Carter was relatively weak in industrialized WWC areas in the northern half of the country, while Dukakis was very strong with that group.

[Vosem]

Carter was generally very weak in the Mountain West. Labor unions also trended left during the 1980s; Carter won union members and their households 59-39 on his way to a 2-point victory in 1976, while Dukakis won them 57-43 on his way to a 7-point defeat in 1988.

Actually, the history of the union vote is sort of fascinating; this one was one of the first questions to be asked in exit polls, and Wikipedia has 'union vote' (including union members' households) statistics going back to 1960. Here's that information (the number in parentheses is lean relative to national vote):
1960: Kennedy 65-35 (D+30)
1964: Johnson 73-27 (D+24)
1968: Humphrey 61-29-10 (D+32)
1972: McGovern 50-48 (D+25)
1976: Carter 59-39 (D+18)
1980: Carter 48-45 (D+13)
1984: Mondale 54-46 (D+26)
1988: Dukakis 57-43 (D+21)
1992: Clinton 55-24-21 (D+26)
1996: Clinton 60-30 (D+22)
2000: Gore 59-37 (D+22)
2004: Kerry 59-40 (D+22)
2008: Obama 59-39 (D+13)
2012: Obama 58-40 (D+14)
2016: Clinton 51-43 (D+6)
2020: Biden 56-40 (D+12)

Before the Obama era, which featured a general trend of union members well to the right of where they had been earlier, the weakest Democrat among union voters, relative to national performance, was Carter in both of his elections.