The states and territories included in the United States Census Bureau's statistics for the United States population, ethnicity, religion, and most other categories include the 50 states and Washington, D.C. Separate statistics are maintained for the five permanently inhabited territories of the United States: Puerto Rico, Guam, the U.S. Virgin Islands, American Samoa, and the Northern Mariana Islands.[1]
As of April 1, 2010, the date of the 2010 United States Census, the nine most populous U.S. states contain slightly more than half of the total population. The 25 least populous states contain less than one-sixth of the total population. California, the most populous state, contains more people than the 21 least populous states combined, and Wyoming, the least populous state, has a population less than any of the 31 most populous U.S. cities.
The United States Census counts the persons residing in the United States including citizens, non-citizen permanent residents and non-citizen long-term visitors.[2] Civilian and military federal employees serving abroad and their dependents are counted in their home state.[3]
Every 10 years, the U.S. Census Bureau is charged with making an actual count of all residents by state and territory. The accuracy of this count is then tested after the fact, and sometimes statistically significant undercounts or overcounts occur. For example, for the 2020 decennial census, 14 states had significant miscounts ranging from 1.5% to 6.6%. While these adjustments may be reflected in government programs over the following decade, the 10-year representative apportionments discussed below are not changed to reflect the miscount.[4]
Based on this decennial census, each state is allocated a portion of the 435 fixed seats in the United States House of Representatives (until the early 20th century, the apportionment process generally increased the size of the House based on the results of the census until the size of the House was capped by the Reapportionment Act of 1929), with each state guaranteed at least one Representative. The allocation is based on each state's proportion of the combined population of the fifty states (not including the District of Columbia, Guam, American Samoa, the Northern Mariana Islands, Puerto Rico, or the United States Virgin Islands).
The Electoral College, every four years, elects the President and Vice President of the United States based on the popular vote in each state and the District of Columbia. Each state's number of votes in the Electoral College is equal to its number of members in the Senate plus members in the House of Representatives.[5]