Who is included

Counted

The population comes from the Census Bureau’s American Community Survey, summing everyone aged 18 and over in each state and each congressional district. The survey counts people where they usually live. Being counted does not depend on being able to vote, so the total includes:

• Adults who are not registered to vote, and adults who did not vote. Registration and turnout play no part in any figure here.
• Adults who are not U.S. citizens, including lawful permanent residents, people on temporary visas, and undocumented residents. The survey does not ask the question in a way that would let this site exclude them, and it does not try to.
• Adults barred from voting by a felony conviction.The rules vary by state; the count does not.
• Adults in institutions, such as prisons, nursing homes and college dormitories, counted at the institution’s address.

The reason is the question the site asks. A percentage here measures how many people the winning side’s members were elected to represent, not how many people voted for them. A member of the House represents everyone in the district, and a senator everyone in the state, whether or not they can cast a ballot. The Methodology page gives the full rule set.

Not counted

• Anyone under 18. The figures are shares of adults, not of the whole population.
• Residents of Washington, D.C. The District has a delegate in the House and no senators, and the delegate cannot cast a vote that counts toward passage. There is no side for its population to be assigned to, so it is outside both the top and the bottom of every fraction.
• Residents of Puerto Rico, Guam, the U.S. Virgin Islands, American Samoa and the Northern Mariana Islands, for the same reason. Each has a non-voting delegate or resident commissioner in the House and no senators.
• Americans living abroad, including service members stationed overseas. The survey counts residents of the United States, so they are not in any state’s total.

About 3.3 million adults live in Washington, D.C., and Puerto Rico, by the same Census release as the total above. They are the people the Census counts and this site does not. The four smaller territories are not broken out in the same Census table, so they are named here and left out of that figure rather than estimated.

The label

The Census Bureau’s term for this population is the voting-age population, and the Methodology page uses it because that is what the source calls it. Everywhere a reader meets a figure, the site says “U.S. adults,” because the formal term is easily heard as “eligible voters,” which is the one thing it is not.