I'd say 1968 would be the last realigning election we've had and have been in that cycle ever since really. It was when the conservatives dropped the Democratic Party and either went third party or to the Republicans. The exception being 1976 due to Carter.
post imagesIn 1972 the southern Dixiecrats completely left the Democratic Party....stripping the Democratic Party down to it's current base of voters and nothing else.
A fluke election occurred in 1976 in the midst of the national confusion and Carter being popular in the South (on the tail of the Watergate Scandal hurting Republicans)
From 1980 to 1988 the Democrats relied on the base of voters they have today and pretty much nothing else for the White House, so they were not competitive in national elections. The three way election of 1992 saw the Democrat's base expand enough to finally be competitive.
The Republicans formed an alliance with the southern conservatives and have been a "coalition party" ever since.
The Democrats seeing a gradual growth in their vote totals shows how the Democratic Party really is more of a single population of voters. The Republicans went through periods of losing voters to third parties and then suddenly gaining them back again later, leading to big spikes and drops. This leads the Republican vote totals to be more sporadic from election to election.
