When asked more specifically about their views on the legality of abortion, half of Americans adopt a middle-of-the-road position, saying abortion should be legal “only under certain circumstances.” Americans with more absolute positions tend to come down on the side of abortion being legal under any circumstances (29%) than being illegal in all circumstances (18%).

Historically, Americans have been most likely to favor the middle position — abortion being legal under certain circumstances. Rarely has the percentage saying abortion should sometimes be legal fallen below 50%, averaging 53% since it was first asked in 1975.

There has been a slight uptick in the percentage saying abortion should always be legal, from 21% in 1975 — two years after the Roe v. Wade decision legalized abortion nationwide — to 29% today. This percentage has varied in the interim, peaking at 33% in 1991, 1994 and 1995, but reverting to 21% as recently as 2009, and averaging 27%.