i was looking at the ratings for Americans for Democratic Action (ADA). In 1982, the last year of lines based off the 1970 Census, the median southern democrat's score was 30. In 1992, the last year of lines based off the 1980 Census, the median score was 65.
Here are the theories
1. all the conservative democrats retired so while the caucus was smaller, it was more liberal
- yet there were 88 southern democrats in 1982 and 93 southern democrats in 1992.
2. The creation of Section 5 districts created more liberal incumbents
- the creation of such districts didn't happen until the 1990 census
One theory is that 1982 was an abnormally bad year as far as the issues are concerned, which is why you had low ratings. Take for example Glenn English of Oklahoma who received a 20 score in 1982 but a 55 score in 1992. Current senator Bill Nelson of Florida also received a 20 in 1982. So is it possible that the democrats were told to start voting more in-line with the leadership so as to not risk being primaried?