This election is nuts. If this trend keeps up we may be looking at the first genuine landslide in decades.
It depends upon the definition of a landslide.
Reagan 1984 (all but Minnesota and the District of Columbia) is one of the all-time slaughters in the popular vote. But in 1984 there was little state-to-state polarization as the Democratic Party was making the tradition from being a strongly-Southern party to a strongly-Northern party while being weak in both regions. The margin of Barack Obama's 2008 victory is close to those of FDR in 1944 and the elder Bush in 1988... Obama won by Reagan-like landslide margins in enough states to win, yet lost several states by 10% or more.
No Democratic nominee has won Colorado or New Hampshire by a 10% margin since 1964, or Virginia by such a margin since FDR in 1944. We may be in unusual territory this year. But Donald Trump is also an unusually awful candidate for President, too.
