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.

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

In the United States, 12% of married couples with at least one spouse in their 30s or 40s have two incomes and no kids.