How easy is it to predict how states will vote in the future?

[TheReckoning]

For example, in the 1980s, California was a swing state, Missouri was a swing state, West Virginia was a blue state, and Nevada was a red state. Now, of course, California and Missouri are safe for their respective parties, West Virginia has flipped, and Nevada is a swing state.

My question is, how easy would it have been to predict this back in the 1980s? Would it be fairly easy for a political scientist, who analyzes trends in voting patterns and shifts in political parties, to tell how these states would be in the 2010s, 30 years in the future?

[TheReckoning]

Bump

[Xing]

Obviously depends on the state (Wyoming is pretty easy to predict), though in general it’s definitely not easy to tell how coalitions will change.

[MarkD]

When you ask a question like this, you've gotta expect a lot of the answers will begin with some form of "it depends."
If you're asking to predict the next election, then most states will predictably vote the same way they have been in recent elections. Only a minority of states will be unpredictable "swing states."
If you asking about presidential elections in the distant future - like twenty-two years from now - then it will be a smaller number of states that will be predictable.
Don't ask a question like this phrased as if all states can be equally predictable, and as if all future presidential elections will all be the same.

[pbrower2a]

1. Who is the politician?

I think that we can all look at Massachusetts, Minnesota, and Rhode Island and see them as three of the toughest states for a Republican nominee for President to win since 1928. Times in which they have voted for the Republican:

1928  MN
1952  MA MN RI
1956  MA MN RI
1972  MN RI
1980  MA
1984  MA RI

That's twelve times altogether for these three states beginning in 1928, and six of those involve Dwight Eisenhower.  Massachusetts, Minnesota, and Rhode Island were somehow the 48th, 49th, and 50th best states for the Republican in 49-state electoral blowouts. I see none of these three states going for the Republican in 2024, so we will have a full century intact.

How a Presidential nominee picks off states depends heavily upon how well he matches the political culture of that state.  Ike fit a bunch of states far better than the usual Republican before or since. 

2. How weak is the loser?

No Democrat has won 400 or more electoral votes since 1964, and the relevant zone for Texas from 1992 to 2020 has been that a Democratic nominee must get 400 or more electoral votes to win Texas, as Texas has straddled 400 electoral votes for a Democrat. (That is over because Texas is increasingly becoming more of a microcosm of the USA. It's now around 350).  On the other side a Democrat would have to get a shellacking in which he lost 400 or so electoral votes to lose... I dunno, Illinois?

3. So far this assumes that the states don't shift in their partisan makeup. Iowa and Ohio used to be much more D than Virginia and Colorado, but that is no longer so. 

Demographic shifts can make all the difference. West Virginia used to be the sort of state that went D in all but R blowouts, the state going for Carter in 1980 and Dukakis in 1988. The coal-mining business used to hire far more workers in West Virginia, and most of them were members of the powerful and politically-active United Mine Workers' Union. Now that coal mining has lost much of its employment, West Virginia no longer has the reliable D voters that it once had. Wal-Mart is the biggest private employer in West Virginia, and it has more influence on West Virginia politics than does the UMWU. We all know  what Wal-Mart believes in in politics; its only liberal trait is its support of welfare because many of its customers use SNAP.

On the other side, if people are moving into a state they likely bring their political culture with them. People do not assimilate to the local political culture, as has been shown in Arizona, Georgia, North Carolina, and Virginia.

4. Urbanization. It should be clear now that politically, Atlanta and Cleveland are much mores similar to each other in their political culture than the rural parts of their states. If Cleveland shrinks along with a bunch of other medium-to-large cities in Ohio, then the rural areas become more important in the vote by default. As Atlanta bloats, Georgia becomes more D.   

A hint on the decline of Ohio: I never see a traffic jam in Toledo, a medium-sized city, unless due to road construction or an accident.

5. Religious shifts. The Upper South, or as I like to call it, the Mountain South, was long a haven for New Deal-style politics. I include Appalachia and the Ozarks. Life got much better there during the New Deal. The people were largely Presbyterian due to heavy Scots-Irish ancestry. The Presbyterian Church is in no way fundamentalist, and it is generally easy-going in its politics. A great religious revival replaced Presbyterianism with fundamentalist versions of the Southern Baptist Church, which is anything but easy-going in politics. Jimmy Carter was going to lose badly in 1980, but the amazing thing is how quickly the Mountain South turned against him. Carter was a Southern Baptist, but not the sort to push an abortion ban or young-earth creationism. Reagan still won the "Rockefeller Democrats" Up North. Carter was not a horrible President in the sense of corruption, extremism, or overall incompetence. The political change doomed him.

6. Breakups of coalitions. The landslide victories of Reagan in 1980 and 1984 and of the elder Bush in 1988 depended upon a coalition of incompatible groups -- the anti-intellectual white Southerners and the Rockefeller Republicans proud of their formal education. That coalition was going to break up, and it would take twelve years. But it did break up with Bill Clinton winning a raft of states that Carter lost in 1976. The break-up is predictable; the manner of the break-up isn't.       

[ملكة كرينجيتوك]

5. Religious shifts. The Upper South, or as I like to call it, the Mountain South, was long a haven for New Deal-style politics. I include Appalachia and the Ozarks. Life got much better there during the New Deal. The people were largely Presbyterian due to heavy Scots-Irish ancestry. The Presbyterian Church is in no way fundamentalist, and it is generally easy-going in its politics. A great religious revival replaced Presbyterianism with fundamentalist versions of the Southern Baptist Church, which is anything but easy-going in politics. Jimmy Carter was going to lose badly in 1980, but the amazing thing is how quickly the Mountain South turned against him. Carter was a Southern Baptist, but not the sort to push an abortion ban or young-earth creationism. Reagan still won the "Rockefeller Democrats" Up North. Carter was not a horrible President in the sense of corruption, extremism, or overall incompetence. The political change doomed him.

6. Breakups of coalitions. The break-up is predictable; the manner of the break-up isn't.       

5 is a pretty good point