Benny, you woke up too late. From the 1950s until 2010 the districts were gerrymandered in strong favor of the Democrats. The House, electoral college and state legislative districts were skewered in the Democrats favor for 60 years so that even though Republicans often got an overall majority of the vote the Democrats still got a majority of the representatives.
Similarly with the Senate, the Democrats overall got less votes but more senators since they owned the South due to their civil war history of supporting the Confederacy.
It was good for them then with no complaints about it being bad for democracy. Well, we can keep the current Republican advantage for sixty years too.
In 2070 lets reassess whether to even the playing field.