Michael Barone's Almanac of American Politics is a marvel. I don't think anyone knows more about the topography of the electoral landscape.
Recently i was reading the 1996 edition. He had some astute observations about the methods the Democrats used to maintain power after 1974 despite the normal ebb and flow cycle of US politics.
A key figure in this was Phil Burton-- an important Democratic congressman from California in the 70s.
To maintain the overall Democratic majority in the House, Burton relied not on the popularity of his issues, about which he entertained no illusions, but on institutional advantages such as redistricting and teaching talented young candidates with superior skills to hold otherwise Republican-leaning seats; he encouraged Democrats to rely on the perquisites of office and pork barrel projects.
Democrats continued to win majorities in every election. They ignored Republicans, routinely used the rules to prevent direct votes on issues on which their stands were unpopular, maintained caucus solidarity and, under the leadership of Tony Coelho in the 1980s, bludgeoned business PACs into contributing to marginal Democrats and not contributing to Republican challengers.
And this is his verdict on the 1994 election which upset the Burton regime:
Most of all the Burton regime ultimately failed because it could not stand the light of day. Talk radio shows showed voters how overbearing and unfair the Democratic majorities were.
Speaking of Barone, this forthcoming book of his could be very interesting.