What's the difference between primaries and caucuses, and why do states have different systems for choosing delegates? Political scientist Josh Putnam explains how delegates are picked, and how the process changed after the 1968 Democratic National Convention.
Political scientist and author runs the Center for the Study of Race, Ethnicity and Politics at UCLA; he talks to Terry Gross about how Barack Obama's campaign is addressing issues touching on race and ethnicity.
When Sen. Hillary Clinton conceded defeat in the Democratic presidential primary in June, she thanked her supporters for making "18 million cracks" in the glass ceiling. Political columnist Katha Pollitt discusses the historical significance of Clinton's presidential bid.