Although a complete understanding of what's going on here requires an explanation of NOMINATE scores and the underlying methodology, this single chart serves as both American Politics in a Nutshell and American Politics at a Glance:


I used to work with the fellow most responsible for developing these measures of ideology, and he is as far to the right as anyone in academia. That is only relevant here inasmuch as it undercuts the glib response that this is just more Ivory Tower Liberal nonsense trying to make the poor GOP look bad. Both parties have moved away from the center since 1970, but…it's fairly clear in these data that one party has done a bit more moving than the other.