In retrospect, which were realigning elections?

[Virginiá]

Realignments generally occur over time and not in a single election. In a way, you could say things are always in flux and one party is rising to power as another dwindles. Right now we are undoubtedly in the process of a Democratic realignment from the old Reagan order. There is an argument to be had (imo) of whether it was 1992 or 2008, but the blue wall states all flipped by 1992 and 2008 marked the beginning of a 2nd round of states emerging as Democratic states as minority and Millennial voting strength grows.

On the other hand, major events can spark a change in thinking and a movement of voters to a party, depending on the circumstances. 1932 is a fine example. This kind of change is very rare and post-FDR I'm not aware of any defining event like it. The Republican realignment of the 60s was not a snap moment - it happened gradually, probably starting in 1948 when the Democrats first began moving towards civil rights. 1964 was a flash point and after that we all know those presidential elections turned out. Republicans simply had more support for a long time, just like Democrats are now beginning to outmatch them.

Also, it's worth noting that there is a heavy generational component to realignments (imo). For instance, right now Millennials are heavily Democratic, and in some emerging battlegrounds/Democratic states, they are the ones powering Democratic success. North Carolina and Florida are decent examples, as the heavily Democratic Millennial/younger genx generation are turning the states blue (in addition to transplants and small coalition shifts), slowly but surely. Eventually, if Republicans fail to make inroads with Millennials and/or the next generation, these states will likely become blue states.

I think it's a little bit easier to look at realignments in terms of time periods and not single elections, because the elections themselves are more like a result of the realignment rather than the trigger.