has there ever been a supermajority in congress
The apportionment of seats in this House of Representatives was based on the Nineteenth Census of the United States in 1970. Both chambers had a Democratic majority. It was the first time either party held a filibuster-proof 60% super majority in both the Senate and House chambers since the 89th United States Congress in 1965, and last time until the 111th United States Congress in 2009. All three super majorities were Democratic party and also were accompanied by Democratic Presidents. As of 2018, this is the most recent Congress to approve an amendment (the unratified District of Columbia Voting Rights Amendment) to the Constitution.
95th United States Congress