How Midterm Elections Work

By: Dave Roos

Stacey Abrams
Georgia Democratic Gubernatorial candidate Stacey Abrams takes the stage to declare victory in the primary on May 22, 2018 in Atlanta. If elected in the November 2018 midterms, Abrams will become the first African American female governor in the nation. Jessica McGowan/Getty Images

It's autumn in America. And just as predictable as the brilliantly changing leaves is the arrival, every two years, of the political lawn signs. When there's a presidential election, lawn signs come out in full force, neighbor pitted against neighbor in yard-based partisanship. But two years after the presidential election, just as the last presidential yard signs are finally pulled, it's time for the midterms.

Midterm elections are held on even-numbered years in between presidential elections. They're called midterms because they coincide with the halfway point of a president's four-year term. For this reason, many political observers look to the midterms as a referendum on a sitting president's performance and a bellwether for which party will take control of the White House.


But midterm elections are about much more than simply testing the political winds for the next presidential election. They are a chance for Americans to go to the polls and vote for their representatives in Congress, state legislatures and local government. While the presidential election isn't decided by popular vote (remember the electoral college?), midterm elections give Americans a chance to vote directly for the politicians who will likely have the greatest impact on their daily lives.

For example, every single seat in the U.S. House of Representatives is up for grabs during midterm elections. That's 435 separate races spread across all 50 states [source:]. When you add in the 34 Senate seats at play during midterms, you begin to understand the political significance of a strong showing on election day. The party that controls Congress has as much, if not more political power than the party sitting in the White House.

Congress not only writes the laws and passes the spending bills, but it decides whether or not to approve the president's Supreme Court nominees and other major political appointees. And in the rare occasions when a president is caught committing a crime, it's Congress that votes whether to impeach. Those are even more reasons why midterm elections are a big deal.

Despite the obvious political importance of midterms, shockingly few Americans actually vote in them. The average turnout of eligible midterm voters from 1972-2016 was a miserable 39.3 percent [source: Skelley and Kondik]. That means, on average, 60 percent of American voters stay home on midterm election day.

Keep reading to learn how midterms got started, what positions are up for election and why it's the civic duty of every American to cast their ballot in these off-year elections. Heck, after reading this article, you might even put up a political lawn sign.


Federal Midterm Elections

Trump, house of reps
President Donald J. Trump delivers the State of the Union address in the chamber of the U.S. House of Representatives in Washington, D.C., 2018. Each House rep only serves two years so they are all up for re-election at midterms. Chip Somodevilla/Getty Images

Put simply, midterm elections exist because not all elected offices in the United States federal government have four-year terms equal to the president. The terms of each elected office in the federal government were debated and settled during the 1787 Constitutional Convention and inscribed in the U.S. Constitution.

In the U.S. federal government, the only elected officials are the president, vice president and congressional representatives. Congress consists of two chambers, the Senate and the House of Representatives, each with its own term lengths and election schedules.


There are 100 U.S. senators, two for each state. Senators serve six-year terms, the longest of any elected official in the federal government. But not every Senate seat is up for election every six years. Instead, according to Article I, section 3, clause 2 of the Constitution, the Senate is divided into three "classes." In the modern Senate, each class consists or 33 or 34 senators. Senate elections are staggered so that one class is up for election every two years.

That's why every midterm election there are at least 33 or 34 senate seats up for a vote. There can be more seats up for election if a senator dies in office or resigns before the end of his or her term. The election schedule is also staggered so that no more than one senate seat from each state is up for grabs during any single election, midterm or otherwise.

According to Constitutional scholars, there were a couple of reasons why the Founding Fathers decided on a six-year term for senators with staggered elections every two years. First, senators are supposed to bring stability and continuity to the federal government. By serving six years, for instance, they may serve under two different presidents.

But that continuity comes with a price. The Founding Fathers worried that senators would become too chummy and permanently conspire for "sinister purposes" [source: U.S. Senate]. So they decided to shuffle the senatorial deck every two years and put a third of the seats up for a vote.

The House of Representatives is a different beast. Representation in the House is based on population, with more populous states getting more seats at the legislative table. The current House of Representatives has 435 members, each serving two-year terms, the shortest of federally elected officials.

The term length of representatives was another lively debate at the Constitutional Convention. The precedent, as set by colonial legislatures and early state legislatures, was that the representatives in state Houses were elected every year and sometimes every six months. The idea was that a short term kept representatives honest to the needs of their constituents. Some of the Founding Fathers believed that federal representatives should also be held to the same tight leash — a one-year term.

Others at the Constitutional Convention argued that one year was far too short to get anything done in the federal government, where legislative business would be more complicated than in the states and colonies. As a practical matter, they also pointed out that it took months for some representatives to simply travel back and forth from their home states to the capital, so they lobbied for a three-year term in the House. In the end, the two sides compromised on a two-year term [source: U.S. House of Representatives].

With two-year terms, every single seat of the House of Representatives is up for election every two years. That's why Americans vote for their House members during both presidential election years and midterms.

But midterms are not just about national races.


State and Local Midterm Elections

Rick Scott
Florida Gov. Rick Scott stops by a Republican call center to rally campaign workers Nov. 4, 2014 in Fort Myers, Florida. Scott beat former Florida Gov. Charlie Crist in the 2014 midterm election. Erik Kellar/Getty Images

If you have voted in midterm elections, there were probably many more races on the ballot than just federal representatives. That's because many state and local governments schedule their elections on the same day as the November midterms.

For example, 36 states elect their governors during midterm elections. In 34 of those states, governors serve four-year terms. Residents of New Hampshire and Vermont elect governors to two-year terms, so gubernatorial elections are held there on both presidential election years and midterms [source:].


And then there are midterm elections for seats in state legislatures. All 50 states, except Nebraska, have bicameral legislatures, meaning there are two chambers similar to the Senate and House of Representatives (most share those names, too) [source:]. State senators serve either two- or four-year terms and most state representatives serve two-year terms (only five states have four-year terms for representatives).

With 50 states and 99 individual legislative bodies, that means thousands of state government seats are up for grabs during the midterms. In the 2018 midterm elections, there are 6,066 state legislative races in 46 states [source: NCSL]. In states with two-year terms for state representatives, all seats are up for election in both presidential and midterm elections. Elections for state senators, like their federal counterparts, are mostly staggered.

Not only are state senators divided into three classes and elected in different years, but in many states the length of the term isn't fixed. In so-called 2-4-4 states, state senators are elected for either two or four years depending on the year of the election. Confused, yet?

The idea behind the 2-4-4 system is to ensure that there is an election every 10 years, because legislative districts are "reapportioned" (aka redistricted) every decade. Because redistricting gives significant advantages to incumbents, some legislatures want to make sure voters have a say in who is in office when those changes are made. Illinois is an exampleof state with a 2-4-4 election schedule.

Statewide ballot measures are another thing that Americans vote on during midterms. In 2018, there are more than 160 proposals on state ballots either created by state legislatures or citizen petitions. Those include everything from financial proposals (taxes, bonds, state pensions) to highly politicized issues like legalization of marijuana and gender identity [source: NCSL].

Then there are myriad city, county and local elections held during midterms. For example, there are hundreds of mayoral seats up for election in the 2018 midterms, including some 70 mayorships in California alone [source: U.S. Conference of Mayors]. Same goes for city council seats, local boards of education, county comptrollers, coroners and more. That would explain all those lawn signs.

Despite the sheer number of elections decided by midterms, relatively few Americans bother to show up to the polls. And those who do tend to cluster into similar demographic groups.


Voter Turnout and Voter Demographics in Midterm Elections

voting in primary election, New York City
A woman arrives at a polling station on New York state's primary election day, Sept. 13, 2018 in the Brooklyn borough of New York City. Drew Angerer/Getty Images

The United States struggles with voter turnout, even during presidential election years. But low voter turnout is compounded during midterm elections that lack the wall-to-wall media coverage of a presidential campaign. Ever since the voting age was lowered to 18 in 1971, voter turnout at midterm elections has averaged 17 percentage points lower than presidential elections (presidential elections: 56.4 percent vs. midterm elections: 39.3 percent) [source: Skelley and Kondik].

Perhaps voter fatigue is partially to blame for the low turnout. Keep in mind that prior to this midterm election, there might have been primary elections held earlier in the year if two or more candidates from the same party were running for the same seat. Worse, there might also have been a runoff election a few months after the primary, depending on the state rules, if the top candidate didn't get more than 50 percent of the vote.


The 2014 midterm election registered the lowest voter turnout in a U.S. federal election since World War II [source: Montanaro]. Only 35.9 percent of eligible voters cast a ballot. The 2010 midterms, however, boasted the highest turnout in the previous 30 years at 41.0 percent, largely because of the Tea Party's success in rallying conservative opposition to President Barack Obama's policies [sources: McDonald, Skelley and Kondik].

Not only is voter turnout at midterm elections low, but different demographic groups are more or less likely to participate in midterm elections. In general, midterm voters are older, whiter and more educated on average than general election voters [source: Skelley and Kondik]. In recent decades, this has had political implications, since older, whiter, more educated voters have been more likely to vote for Republican candidates (although the more-educated demographic trended Democrat in the 2016 election).

Since 1978, Republican voters have been more likely to show up for midterms by an average of 3 percentage points. The Republican turnout advantage has been greatest during midterms when a Democratic president is in the White House. In three such midterm elections, Republican voter turnout was 6 percentage points higher than Democrats (1978, 1994, 2010) [source: Enten].

From exit poll data, it's clear that non-white voters continue to make up a smaller percentage of midterm voters compared with presidential elections. For example, in the 2008 presidential election, 26 percent of all voters identified as non-white, but in the 2010 midterms, that share was only 23 percent. The same 3-point drop occurred between the 2012 presidential election and the 2014 midterms. Since non-white voters are more likely to identify as Democrats, that's another midterm advantage for Republicans [source: Skelley and Kondik].

Even with historic imbalances in voter turnout, one trend has proved true in almost every midterm election in the past 50 years — the party that controls the White House gets pummeled. In the next section, we'll explore the so-called "midterm penalty" and other theories for midterm power transfers.


Presidential Popularity and 'The Midterm Penalty'

Midterms are typically bad news for the sitting president and his party. In all but three of the past 26 midterm elections, the party in the White House has lost seats in either the Senate, the House of Representatives or both [source: Enten]. The phenomenon even has a name — the midterm penalty.

The conventional explanation for the midterm penalty is that midterms function as a referendum on the president's popularity. If the president has performed well in the first two years of his term — or the economy has performed well, as is often the case — the damage is limited to a few seats in either chamber. But if voter sentiment has turned sharply against the president and his party, the midterm losses can be crippling.


When you look at historic job approval data and midterm results, this explanation seems to hold water. Starting in 1946, when a president has registered a job approval rating over 50 percent at the time of the midterm, his party has only lost an average of 14 seats in the House of Representatives. When his approval rating has dropped below 50 percent, his party has lost 36 seats on average [source: Jones].

Those are just the average losses. Individual midterm results make an even stronger case for the midterm penalty being linked to the president's performance. At the time of the 2010 midterms, for example, President Barack Obama's approval rating slipped to 45 percent and his party suffered heavy losses — 63 seats in the House and six in the Senate. Similarly, President George W. Bush's approval rating was a dismal 38 percent for the 2006 midterms and his party lost 30 seats in the House and six in the Senate [source: Jones].

But there are also competing theories to explain the midterm penalty. One is called the coattail effect [source: Murse]. The coattail effect is particularly strong when a president is swept into office in a landslide victory, like Barack Obama in 2008. Given Obama's popularity and wide appeal with Democrats, more people turned out at the polls in 2008 and 2012 to vote Democrat. Since most voters cast ballots along party lines, Democratic candidates down the ticket got a boost, from senators to House representatives to mayors. Those Democratic winners were, in effect, riding Obama's coattails.

During midterms, however, there is no coattail effect, or at least far less of an effect. There may be a few high-profile Senate races that draw larger numbers of partisan voters to the polls, but nothing close to presidential contests. The result is that the president's party, regardless of the president's performance or popularity, takes a hit during the midterms, because many of the voters who were excited to vote in the general election lack motivation to participate in the midterms.

A second theory for the midterm penalty is called negative voting. Political science research shows that people are more likely to vote when they have negative opinions of the president than when they have positive ones. At first, this data seems to support the theory that midterms are a referendum on the president. But there's a difference. Even if half of all voters support the president, fewer positive voters will show up at the polls compared the other 50 percent who hate him. So the midterm results may look like a resounding "protest vote" even though half the country has nothing to protest [source: Erikson].

To wrap things up, let's take a look at some of the most remarkable midterm results in U.S. election history and their lasting political consequences.


Historic Midterm Elections

Grover Cleveland, second address
President Grover Cleveland reads his second inaugural address at the Capitol building in Washington, D.C., March 4, 1893. Just a year later, his Democratic party was punished with the biggest political midterm reversal on record. Wikimedia Commons

The following are some of the worst trouncings, rarest victories and biggest transfers of congressional power in U.S. midterm history [sources: Frail, Murse and Branigin]:

  • 1894: In 1892, Grover Cleveland, a Democrat, became the first president to be elected to two non-consecutive terms. But soon after his re-election, the U.S. entered a crushing economic depression compounded by a huge railroad strike. Angry voters punished Democrats in the midterms, giving Republicans an additional 116 seats in the House and five in the Senate. It remains the biggest midterm political reversal on record.
  • 1930: After President Herbert Hoover, a Republican, failed to take action to stem the spread of the Great Depression, voters gave Democrats 49 seats in the House and eight in the Senate. The groundswell of labor unionists, farmers and racial minorities that opposed Hoover in the midterm would put Franklin D. Roosevelt in office and pave the way to the New Deal.
  • 1934: Riding the popularity of his New Deal policies, FDR's Democratic party picked up nine seats in the House and nine in the Senate, the greatest midterm performance ever for a party in control of the White House.
  • 1966: In the 1964 presidential race, Democrat Lyndon Johnson crushed Barry Goldwater with 90 percent of the electoral vote. But his support for the Vietnam War and the passing of progressive Civil Rights laws and Medicare cost him popular support. Democrats not only lost 47 seats in the House and three in the Senate, but Republicans also formed a conservative voting bloc that would put Richard Nixon in the White House in 1968.
  • 1974: Republicans took a beating in the midterms held a year after Richard Nixon's resignation over the Watergate scandal, losing 48 seats in the House and five in the Senate.
  • 1994: United by Newt Gingrich's "Contract for America," Republicans mounted a conservative revolution against President Bill Clinton, winning 52 seats in the House and eight in the Senate.
  • 2006: After gaining Republican seats in the 2002 midterm, held a year after the 9/11 attacks, Republican President George W. Bush took a "thumpin'" (his words) in the 2006 midterm. Voters frustrated with the administration's handling of the wars in Iraq and Afghanistan gave Democrats 30 seats in the House and six in the Senate.
  • 2010: The Tea Party rode conservative opposition to Democratic President Barack Obama to a massive Republican victory in the midterms, taking 63 seats in the House and six in the Senate, the most seats lost in a single midterm election since 1938. Obama memorably pronounced the loss a "shellacking."

For lots more information on U.S. elections and the fascinating (often nauseating) world of politics, check out the links below.


Lots More Information

Author's Note: How Midterm Elections Work

OK, I'll admit it. I don't get as excited about midterm elections as I do about presidential elections, and there's a very good chance that I have skipped voting in several midterms since turning 18 just a couple (dozen) years ago. But after researching and writing this article, I understand the true significance of midterms in determining not only who controls the Congress, but also who is in charge of things like redistricting on the state level. I fully plan on voting in every midterm from now on, but I seriously doubt I will ever plant a political yard sign in my front lawn. My neighbors don't like me enough as it is.

Related Articles

More Great Links

  • Enten, Harry. "Do Republicans Really Have a Big Turnout Advantage in Midterms." FiveThirtyEight. Jan. 9, 2018 (Sept. 24, 2018)
  • Erikson, Robert S. "The Puzzle of Midterm Loss." Southern Political Science Association. Nov. 4, 1988 (Sept. 24, 2018)
  • Frail, T.A. "Top 10 Historic Midterm Elections." Oct. 13, 2010 (Sept. 24, 2018)
  • Jones, Jeffrey M. "Avg. Midterm Seat Loss 36 for Presidents Below 50% Approval." Gallup. Aug. 9, 2010 (Sept. 24, 2018)
  • McDonald, Michael P. "Who Voted in 2010, and Why It Matters for 2012." Huffington Post. Nov. 4, 2010 (Sept. 24, 2018)
  • Montanaro, Dominico. "2014 midterm election turnout lowest in 70 years." Nov. 10, 2014 (Sept. 24, 2018)
  • Murse, Tom. "Why the President's Party Loses Seats in Midterm Elections." ThoughtCo. Aug. 14, 2018 (Sept. 24, 2018)
  • National Conference of State Legislatures. "State Legislative Races and Ballot Measures." Sept. 5, 2018 (Sept. 24, 2018)
  • "Nebraska Unicameral" (Sept. 24, 2018)
  • Skelley, Geoffrey and Kondick, Kyle. "How Midterms Do (and Do Not) Differ From Presidential Elections." University of Virginia Center for Politics. March 2, 2017 (Sept. 24, 2018)
  • The United States Conference of Mayors. "Election Results" (Sept. 24, 2018)
  • United States House of Representatives. "Biennial Elections." History, Art and Archives (Sept. 24, 2018)
  • United States Senate. "The Senate and the United States Constitution" (Sept. 24, 2018)
  • "Midterm Congressional, State and Local Elections" (Sept. 24, 2018)