What constitutes a landslide victory?

[zorkpolitics]

Since the Constitution defines the Presidency as elected via the Electoral College, a landslide should be defined based on the EC margin.   I would define a landslide as >90% (>484) of the Electoral votes.  This definition recognizes 4 landslides in the last 50 years:
1964 LBJ           486    (61 % PV)
1972 Nixon       520   (60% PV)
1980 Reagan     489    (51% PV)
1984 Reagan     525   (58% PV)
The only outlier in PV is 1980, but then a Anderson took 9% of the vote and Carter polled only 41%.
If one dropped the landslide definition to >75% (>403) EV, then an additional 3 landslides occurred:
1988 Bush             426 (53% PV)
1956 Eisenhower  457 (57% PV)
1952 Eisenhower  442 (55% PV)

Overall, a landslide should be an outstanding accomplishment, so I’ll stick with the 90% cutoff.

[zorkpolitics]

A landslide is in perception.

Good point, I stick with my earlier post, a Landslide is a 90% win in the Electoral College.  Once all those states are displayed on election night, all the same color, no one will doubt its a Landslide win for the winning candidate.
The popular vote is just an interesting, non-Constitutionally relevant, statistic