The polarization in this country is so high now (including geographic polarization) that it borders on impossible for a candidate to do well in both a state like New York and a state like Oklahoma and win them both (even though FDR, Eisenhower, LBJ, Nixon and Reagan managed to).
I'm going to be slightly more realistic and suggest a 44-state landslide, like the ones FDR got in 1932 and Reagan got in 1980. (Carter also won DC in 1980, which could not vote in 1932). The losing candidate wins 6 states in each case.
