The article assigns blame to Reagan because he was the President when “the great divide really took off” without mentioning Congress. Democrats controlled the House the entirety of Reagan’s time, and the Senate for 2 years. I think it’s fair to direct your criticism to both the earlier commenter, as well as the…

July 2009 through February 2010

A Democrat filled Kennedy’s seat until Scott Brown’s election. While it didn’t last long, Obama did have a filibuster-proof majority for a short period.