What Happens to a Senate Seat When It Goes Empty: The 45-State Map of Appointment Power

The rule the Seventeenth Amendment left behind

Before 1913, state legislatures chose United States senators. The Seventeenth Amendment, ratified that year, moved the choice to the voters and set out what happens when a seat opens between elections. The amendment directs a state's governor to issue a writ of election to fill the vacancy, and it lets the state legislature empower the governor to make a temporary appointment in the meantime (Congressional Research Service, U.S. Senate Vacancies: How Are They Filled?).

Almost every state took that option. Forty-five states now authorize their governors to fill a Senate vacancy by appointment (Congressional Research Service, U.S. Senate Vacancies). The appointment is the fast path: it keeps the state at full strength in the chamber while the slower machinery of an election runs. The death of Sen. Lindsey Graham of South Carolina on July 11, 2026 put that machinery in motion in real time.

Three different clocks

The states that allow appointment do not agree on how long the appointee should serve, and the difference matters. In 34 states, the governor names a senator who holds the seat until the next regularly scheduled general election, when voters fill the balance of the term (Congressional Research Service, U.S. Senate Vacancies). That can mean a single appointee serves well over a year.

The remaining 11 appointment states require a stand alone special election on an accelerated schedule, so the appointee is a short term placeholder rather than a long term stand in (Congressional Research Service, U.S. Senate Vacancies). And a small group of states, about five, allow no gubernatorial appointment at all; the seat simply stays empty until voters fill it (Ballotpedia, Filling vacancies in the U.S. Senate). South Carolina belongs to the appointment group: Gov. Henry McMaster may name an interim senator, and a special primary is set for August 11, 2026 to choose the nominees for the November ballot (The Washington Post, July 12, 2026; CNN, July 12, 2026).

Why a vacancy usually keeps its party

The appointment power is why a single death rarely swings the Senate. The governor picks the interim senator, and governors almost always pick from their own party. The party that holds the governorship therefore tends to hold the seat through the appointment, regardless of which party the departed senator belonged to. Some states go further and require the appointee to come from the same party as the senator who left, narrowing the choice further (Ballotpedia, Filling vacancies in the U.S. Senate).

That is the machinery behind the numbers on the 2026 Senate races board. A seat can lose its occupant without moving on the flip likelihood scale, because the appointment holds the party line until voters weigh in. It also explains why the governorship carries Senate stakes that rarely make the headline. The 2026 governor races ranking tracks contests that, in a vacancy year, can decide who names a United States senator.

How often it actually happens

Appointment is not a rare emergency. States have used it steadily since the amendment took effect, filling seats opened by death, resignation, and elevation to other office throughout the past century (U.S. Senate, Appointed Senators, 1913 to Present). At any given time, a handful of sitting senators first entered the chamber by a governor's pen rather than a ballot.

Death in office, the trigger in South Carolina, is the rarer cause now than it once was. Roughly 300 senators have died in office since 1789 (U.S. Senate, Senators Who Have Died in Office). But the pace has fallen sharply. From 1789 through 1972, an average of 1.53 sitting senators died each year; since 1973, that average has dropped to 0.41 per year (Smart Politics, University of Minnesota, 2023). The stretch between the death of Sen. John McCain in August 2018 and the death of Sen. Dianne Feinstein in September 2023 was the fourth longest gap without a Senate death in the nation's history (Smart Politics, University of Minnesota, 2023). Modern medicine and shorter careers of the very old have made the empty chair a less frequent sight, even as the chamber has grown older on average.

The bottom line

The design is built for continuity. A seat opens, a governor fills it within days in most states, and the state keeps its full voice in the Senate while an election runs on a defined calendar. The choice of who fills the gap belongs to one elected official, the governor, whose own party almost always keeps the seat until voters have their say. That is why a death that dominates a news cycle can leave the balance of the chamber exactly where it was. The person is irreplaceable; the vote, by design, is not left empty for long.