Racial categories, which have been on every U.S. census, have changed from decade to decade, reflecting the politics and science of the times.

How the U.S. government measures race has changed substantially since censuses began in 1790. Today, Americans differ on whether the government should ask about race.

One of the most unusual aspects of the 2008 presidential campaign is its changing dynamics and how they affect political dialogue. Would a race between John McCain and Barack Obama, or John McCain and ...