Here's a fact I found interesting that's reflective of the country Joe Biden now leads: only six states have Senators from (or caucusing with) different parties, which is the lowest such number since at least the 1980s. (Those states are Maine, Montana, Ohio, Pennsylvania, West Virginia, and Wisconsin.)
It might have been lower at some point prior to the 1980s, but that would have been in the days of either broad coalitions (such as the FDR's New Deal coalition) or extreme polarization (such as around the Civil War).
EDIT: Further, in the forty-four states without split delegations, that state gave its electoral votes (or, in the case of Nebraska, its two statewide electoral votes) to the Presidential candidate of the same party as its Senators.