What issues has the south led on?

I am asking this for a friend. We were talking about NY legalizing same sex marriage, which led to a discussion about civil rights and that the north seems to lead on issues like this. In fact, Gov. Cuomo included in his speech the other day that NY many times leads the way on these sorts of things if I am not mistaken.

So, he was wondering what significant issues in American history has the south led and now have become the fabric of the country.

Does not have to be social issues, can be anything at all.

Even southerners who have stood out in changing America, even when the majority of the south resisted.