I've had a number of posts on various aspects of public opinion about abortion, but none of them give a general overview, so that's what I'll try to do here. Although there are some puzzles on specific points, I think that a pretty clear and consistent picture emerges.
1. Overall distribution of opinions: the most straightforward question is one by Gallup, which asks if abortion should be legal under any circumstances, under only certain circumstances, or illegal in all circumstances. The last time it was asked (2021), the percentages were 32%, 48%, and 19%. If you ask about specific circumstances, support for the "always" and "never" positions seems lower--that's reasonable, since someone answering the general survey question isn't going to have time to think about all the possible circumstances. If you ask about saving the life of the woman, support is 90% or more. If you ask specifically about abortion in the last trimester, only 8% say that it should always be legal. The Gallup numbers are a pretty good summary if you understand them as being about roughly the first half of pregnancy and implicitly add the qualifier "except for rape, incest, or to save the life of the woman" to the last option.
2. Change: there has been little change in the overall distribution of opinions since the 1970s. If you look closely, you can find some changes, but they are small.
3. Gender: there is little difference in the opinions of men and women. Some surveys find that women are a little more likely to support legal abortion, others find that men are--see this post. I will have a post documenting this point in more detail in the next week or so.
4. OK, what does matter for opinions?: Education and age--more educated people and younger people are more favorable. Over time, younger generations replace older ones, and younger generations tend to be more highly educated, which would increase support for legal abortion. Given the absence of a clear trend, there must be age and/or period effects working in the other direction. Religion--religious people, especially evangelical Protestants, are more opposed. Region--people in the South are more opposed. This is partly but not entirely due to differences in religiosity. I haven't looked closely, but I think it's specifically white Southerners who are more opposed and that regional differences among blacks are smaller. Those are the biggest factors. There is also some difference by race, with blacks more in favor of legal abortion; there's not much difference between Hispanic and non-Hispanic whites.
5. Roe v. Wade: most people say that the Roe v. Wade decision should not be overturned. For example, a CNN survey from January asked how you would feel if the Supreme Court "completely overturned" the decision: 14% said happy, 12% satisfied but not happy, 25% dissatisfied but not angry, and 35% angry. A 2019 survey for NPR/PBS News Hour offered a number of options about what the court should do: 13% said overturn it; 26% said keep it but add more restrictions; 14% said keep it but reduce some restrictions; 21% said expand it to establish the right to abortion under any circumstances; 16% volunteered keep it the way it is, with 11% don't know. That's a combined total of 39% for more restrictions and 35% for fewer. (Some surveys ask a general question about whether there should be more or fewer restrictions than there are today, and get similar results).
6. Parties: more people feel that they are closer to the Democrats on abortion and trust the Democrats to do a better job of dealing with abortion. The differences aren't large, but they've been around for a long time and are pretty consistent. For example, an AP survey from July 2021 asked "which party do you trust to do a better job of handling abortion policy?" 27% said the Republicans, 40% said the Democrats, 11% both equally, and 21% neither. Back in 1989, the Gallup and Harris polls asked similar questions: Gallup showed a 37%-34% edge for the Democrats and Harris showed a 43%-29% edge.
[Data from the Roper Center for Public Opinion Research]