Each state has two senators, and with 50 states in the union that adds up to 100 senators total. The rule is fixed by the Constitution and does not shift with population, so every state gets the same number regardless of size.
Why the Number Is Two
The two-senator rule comes out of the Great Compromise of 1787 at the Constitutional Convention. Smaller states worried that a legislature tied purely to population would drown out their voice, while larger states wanted representation matched to their headcount. The deal split the difference: the House of Representatives reflects population, and the Senate treats every state as an equal. Article I, Section 3 of the Constitution locks this in, declaring that “the Senate of the United States shall be composed of two Senators from each State.”1Congress.gov. Constitution Annotated Article I Section 3
The Rule Ignores Population
That parity is the Senate’s defining feature. California, with roughly 39 million residents, and Wyoming, with about 580,000, each send two senators to Washington. Proportional representation lives in the House, where California holds dozens of seats and Wyoming holds one. The Senate exists precisely to balance that out.
Who Does Not Get Senators
Only states have senators. Washington, D.C., Puerto Rico, Guam, the U.S. Virgin Islands, American Samoa, and the Northern Mariana Islands do not elect voting members of the Senate. These territories and the District send non-voting delegates to the House, but they have no presence in the Senate at all. Roughly four million Americans living in U.S. territories and D.C. therefore have no say in Senate votes on legislation, treaty approvals, or federal appointments.
Six-Year Terms, Staggered by Class
Even though each state holds two seats, both seats almost never come up for election in the same year. Senators serve six-year terms, the longest of any elected federal officeholder, and Article I, Section 3, Clause 2 divides the body into three classes so that roughly one-third of all seats face voters every two years.2Congress.gov. ArtI.S3.C2.1 Staggered Senate Elections In any given cycle, about 33 or 34 seats are on the ballot.
The staggering is deliberate. It keeps institutional knowledge in the chamber and prevents a single wave election from replacing the entire body overnight. The House, by contrast, puts every seat up every two years, which makes it far more responsive to short-term shifts in public opinion.
How a State Fills a Vacant Seat
When a senator dies, resigns, or is expelled, the 17th Amendment governs what happens next. The governor of the affected state must call a special election to fill the vacancy. In the meantime, most state legislatures have authorized the governor to appoint a temporary replacement who serves until voters pick a permanent successor.3Congress.gov. U.S. Constitution – Seventeenth Amendment
Not every governor has a free hand. Ten states require the appointee to belong to the same political party as the senator who left the seat. The timeline for the special election also varies: some states schedule one quickly, while others wait until the next regularly scheduled general election. Either way, the state’s count is restored to two, because the Constitution does not permit any state to hold fewer or more.
The 17th Amendment itself changed how senators reach office in the first place. Originally, state legislatures chose senators. Ratified in 1913, the amendment gave that power directly to voters, making the Senate an elected body for the first time.3Congress.gov. U.S. Constitution – Seventeenth Amendment