As recently as the early 1970s, abortion was not a party-line issue: When the Supreme Court ruled on Roe v. Wade in 1973, Democrats actually polled as being less supportive of abortion rights.
But all that changed in 1976, when both political parties adopted official planks on the issue. In a recent paper, University of West Georgia's Daniel K. Williams recounts the unexpected challenge that the then "pro-choice majority" in the Republican national convention encountered that year:
