How US Midterm Elections Work

The House has 435 voting members, each elected from a single district for a two-year term. Seats are divided among the states by population after each ten-year census (a process called apportionment), and every state gets at least one representative (Article I, Section 2). The 435 figure is set by federal statute, not by the Constitution — Congress could change it by passing a law. The House also seats six non-voting members: delegates from the District of Columbia and four territories, and a resident commissioner from Puerto Rico. Because every seat is up every two years, the entire chamber can flip in a single night.

The Senate has 100 members, two per state, serving six-year terms. The Constitution split senators into three classes so that roughly one-third of the chamber is elected every two years (Article I, Section 3). That staggering is deliberate: the framers wanted one chamber that could not be replaced wholesale in a single election. Since the 17th Amendment (ratified 1913), senators have been elected directly by voters rather than chosen by state legislatures. In a given midterm, only the states whose seat in that class is expiring hold a regular Senate race — so some states have no Senate race at all, and a state's two seats are never in the same class.

Most states elect their governor in midterm years, usually to a four-year term; a few elect governors in odd-numbered years or alongside the presidential race. Midterm ballots also commonly include other statewide offices — attorney general, secretary of state, treasurer and, in some states, elected judges or school superintendents. These offices matter for national politics: governors sign or veto district maps in many states, attorneys general bring lawsuits against federal policies, and secretaries of state administer elections.

Most state legislative seats are also filled in even-numbered years. State legislatures write election law, pass state budgets and, in many states, draw both congressional and state legislative district maps. That is why political strategists treat midterm state legislative races as long-term investments: a legislature elected in a year ending in 0 typically controls redistricting after that year's census, shaping elections for the following decade.

Many midterm ballots include measures that let voters decide a policy question directly. Legislatures can refer questions to voters — in most states, amendments to the state constitution must be approved by voters this way. In some states, citizens can also put measures on the ballot themselves by gathering a set number of petition signatures. There is no national ballot measure process in the United States: all ballot measures are state or local.

Before the general election, each party chooses its nominees, almost always in state-run primary elections held between late winter and early fall. Each state sets its own primary date and its own rules for who can vote. Because most House districts lean strongly toward one party, the primary is often the real contest: whoever wins the dominant party's primary is very likely to win in November. Primary electorates are smaller and more ideological than general electorates, which is one reason incumbents sometimes worry more about a primary challenger than about the other party.

After the primaries, nominees campaign through the fall. Voting itself now usually begins well before Election Day. Every state offers some form of absentee or mail voting, and most offer in-person early voting, though the rules — who qualifies, how long the window is, when ballots must arrive — differ by state. Election Day is the last day to vote, not the only one.

On election night, the numbers on TV are unofficial returns reported by local officials. When a news organization 'calls' a race, that is a projection by the news organization, not a legal result. The official count comes during the canvass in the days and weeks after the election: local officials reconcile the number of ballots with the number of voters, count remaining mail and provisional ballots, and resolve problems. Because states differ in when they may start processing mail ballots, the order in which vote types are reported can make early returns swing in one direction and then the other — a pattern that reflects counting order, not fraud.

After the canvass, local officials certify their results and send them to the state, where a designated official or board certifies the statewide outcome on a deadline set by state law. For the Senate, the governor issues a certificate of election to the winner; for the House, state officials send certificates to the Clerk of the House. The new Congress convenes on January 3 (20th Amendment), and each chamber is 'the Judge of the Elections, Returns and Qualifications of its own Members' (Article I, Section 5) — meaning the House and Senate themselves have the final word on a disputed seat.

Fewer people vote in midterms than in presidential elections. The electorate that does show up is not a random sample of the country — midterm voters tend to be older, more habitual and more politically engaged than the larger presidential-year electorate. Recent midterms have been unusually high-turnout by historical standards. According to the US Census Bureau's Current Population Survey, 53.4% of the citizen voting-age population voted in 2018 and 52.2% in 2022 — the 2022 figure the second highest for a non-presidential year since 2000. Registration in 2022 reached 69.1% of the citizen voting-age population, up from 66.9% in 2018.

The most consistent pattern in American elections is that the president's party tends to lose ground in Congress at the midterm. The American Presidency Project at UC Santa Barbara, looking at the 23 midterms from 1934 through 2022, finds the president's party lost an average of 27 House seats and 3 Senate seats. In that period, the president's party gained House seats only three times and Senate seats seven times, gained in both chambers only twice, and lost seats in both chambers about two-thirds of the time. Recent examples from the same source: in 2018 the president's party (Republicans) lost 40 House seats but gained 2 Senate seats; in 2022 the president's party (Democrats) lost 9 House seats but gained 1 Senate seat.

After each decennial census, House seats are reapportioned among the states, and states redraw district lines so each district has roughly equal population. Who draws the lines depends on the state: in many states it is the legislature (with the governor's signature or veto), while others use a commission. Gerrymandering is drawing lines to advantage a party or group — typically by 'packing' opposing voters into a few districts or 'cracking' them across many. Maps shape midterms because they decide how many seats are genuinely competitive before a single vote is cast.

The 2026 federal general election is on Tuesday, November 3, 2026 (Federal Election Commission). This section deliberately lists only structural facts from official sources — no candidates, race ratings or predictions. For the full, live calendar of elections in 2026, use the Model Diplomat 2026 elections page.

For a class project, a Congressional Debate brief or a current-events round, build your understanding of a race from primary sources outward. Start with official results and filings, then use news and analysis for context, and label anything that is a forecast as a forecast.

Midterms touch nearly every part of the AP US Government and Politics course: constitutional design (terms and staggering), Congress (majority control and oversight), federalism (state-run elections), political participation (turnout and voter behavior), parties and campaigns, and the Supreme Court's redistricting cases. Questions are rarely about memorizing a single fact — they ask you to connect a feature of the system to a consequence.

Midterm dynamics show up as argument material far beyond AP Gov. In Congressional Debate, whether a bill can realistically pass a divided Congress is a legitimate framing point. In Public Forum, a resolution about US policy often turns on what Congress will fund or block. In Model UN, if you represent the United States — or any country negotiating with it — the domestic political calendar affects what commitments the US delegation can credibly make on treaties, funding and sanctions.