By virtue of being the first black president—and being re-elected—Barack Obama has already been a transformational figure in American politics and history. We are not a "post-racial" society, certainly. But the president has transformed the sense of what is possible in the country. Some people have taken that as a good sign, others...not so much.
As for policy, if the Affordable Health Care Act gets up and runs effectively, that will continue the transformation of American attitudes about the proper relationship between government and citizen. The way we do health care (or don't do it) is one of the principal differences between the U.S. and other industrialized nations. "Obamacare" will cease to be a pejorative—actually, it's already on its way out of being that. If he is able to get support for his very modest gun control initiative—an unforeseen issue—and get comprehensive immigration reform, there is little reason to doubt that his would not be seen as a vibrant and transformative presidency.
Annette Gordon-Reed is the Charles Warren Professor of American Legal History at Harvard University and the Carol K. Pforzheimer Professor at the Radcliffe Institute for Advanced Study.
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