STARTING in 1790, and every 10 years since, the census has sorted the American population into distinct racial groups. Remarkably, a discredited relic of 18th-century science, the “five races of mankind,” lives on in the 21st century. Today, the census calls these five races white; black; American Indian or Alaska Native; Asian; and Native Hawaiian or other Pacific Islander.

The nation’s founders put a hierarchical racial classification to political use: its premise of white supremacy justified, among other things, enslaving Africans, violent removal of Native Americans from their land, the colonization of Caribbean and Pacific islands, Jim Crow subjugation and the importation of cheap labor from China and Mexico.

An indigenous person from Peru, Bolivia or Guatemala is Hispanic, but if she “maintains tribal affiliation or community attachment,” she might also be counted as part of a racial group that includes the Inupiat and Yupik peoples of Alaska.

Are Australian immigrants whites or Pacific Islanders? (The Census Bureau’s own documents are unclear on this.)