I've seen many people express concern about the anti-abortion stance of Trump (and the likely more strongly held anti-abortion stance of Pence), especially since he'll be filling one or more Supreme Court vacancies and it was a Supreme Court decision that legalized abortion America-wide in the first place.

But does the Supreme Court regularly go back and reconsider old cases? What's the actual chance of Roe v. Wade being overturned? In the third debate, Trump seemed to think it would happen, but I don't have a lot of faith that he knows how things work.

TRUMP: Well, if we put another two or perhaps three justice on, that's really what's going to be -- that will happen. And that'll happen automatically, in my opinion, because I am putting pro-life justices on the court. I will say this: It will go back to the states, and the states will then make a determination.

So for all the Americans here, is there an actual chance of it being overturned? If not, are there other avenues that he could take at the national level to block access to abortion or make it illegal somehow? It seems that challenges generally come from the states. Is that just because Republicans more often control them, or because states have more authority there?

Just trying to understand better some of the possible effects of his win.