What word means a group of voters?

The word that means a group of voters, on the USCIS reading vocabulary list, is Constituency. A constituency is the body of voters in a defined geographic area who elect a representative to a legislature, and the term also refers more broadly to the people whose interests a public official represents.

In the United States the most common constituencies are congressional districts, each of which elects one member to the U.S. House of Representatives. The Constitution requires the apportionment of House seats among the states based on population, with each state receiving at least one seat. After each ten-year decennial census, the 435 House seats are reapportioned among the states, and individual states draw congressional district boundaries through a process called redistricting. As of the apportionment based on the 2020 census, each congressional district represents roughly 760,000 people, although the population per district varies substantially across states.

Senators have a different kind of constituency: each U.S. Senator represents the entire population of his or her state rather than a smaller district, and so a Senator from California represents about 39 million people while a Senator from Wyoming represents about 580,000. Presidents and Vice Presidents are sometimes said to have a national constituency because they are the only federal officials elected by voters in all states (through the Electoral College).

State legislative districts, city council wards, and judicial districts also have their own constituencies. The word is also used metaphorically for groups of supporters who share interests, such as labor, agricultural, or business constituencies.

On the reading test Constituency may appear in a sentence about elections or representation, although it is less common than simpler vocabulary like vote or elects.