America swung 13 points left between 1972 and 1980, from 61-38 R in 1972 to 51-41 R in 1980. Here's the state-by-state swing map:
Reagan actually gained in much of the Southwest, particularly California (!!). Much of the swing against him was concentrated in the South, where totally insane 40-point swings were basically routine.
The last Republican nominee to win California by a larger margin than Reagan in either 1980 or 1984 was Hoover in 1928.
1. Reagan 1980: R+16.8
2. Reagan 1984: R+16.2
3. Eisenhower 1952: R+14.6
It really seemed like California maxed out for Republicans at a presidential level at around 14-15 points as despite massive landslides in 1956/1972, the Republicans never could cross that amount until Reagan got a home state bump but even then its clear the Democrats had a pretty large floor in California.
1984 was still technically left of the center, first time of real permanence since 1956 and 1972 were islands.
