How midterm elections have changed Congress since 1946

Today, Americans are heading to the polls for midterm elections, where the entire House and 35 Senate seats will be up for grabs. So how have these elections panned out in the modern era?

Since 1946, when Republicans ended a 14-year period of total Democratic control in Congress, midterm elections have been mostly contested starting in the Reagan era. Between 1946 and 1954, both parties swapped control of Congress. However, starting in 1955, the Democrats had majorities in both houses of Congress after every congressional election until the 1980 Reagan Revolution.

The Republicans grabbed back the Senate for the first six years of the Reagan administration, while the Democrats retained the House. Since 1988, in 15 Congressional elections, the Republicans have retained a majority in the entire Congress five times on Election Day and the Democrats four times. (After the 2000 election, the Democrats gained a deciding vote in the Senate after a Republican became an Independent in May 2001.)

In two elections, 1994 and 2016, both the House and the Senate changed control. In three cases, different parties gained control of just the House or the Senate in the same election, and in one instance (2012), the Congress remained split after an election.

Examining just the midterm elections after 1980, the picture is equally mixed. In nine midterms, the balance of power in Congress has remained the same in four elections. Those two elections in 1994 and 2006 saw voters change the majority party in the Senate and House at the same time. And in three other cases, the Republicans picked up the House or the Senate from the Democrats.

In the past five midterm elections, the Republicans gained control of the Senate in 2014, the House in 2010, and the Senate in 2002. The Democrats gained both the House and Senate back in 2006. So it has been 20 years since a midterm election didn’t result in a change of control in at least one chamber of Congress when the Republicans kept the House and Senate in 1998.

For the record, the last time the Democrats gained back the House and didn’t win the Senate in a midterm election was in 1930, when Herbert Hoover was President.

For official historical results, you can go to the House's official page at: https://history.house.gov/Institution/Party-Divisions/Party-Divisions/

and the Senate's official page at: https://www.senate.gov/history/partydiv.htm

Congressional Election Control Since 1998

Election Year	Senate	House
1988	Democrats Hold	Democrats Hold
1990	Democrats Hold	Democrats Hold
1992	Democrats Hold	Democrats Hold
1994	Republicans Gain Control	Republicans Gain Control
1996	Republicans Hold	Republicans Hold
1998	Republicans Hold	Republicans Hold
2000	Split After Republicans Hold	Republicans Hold
2002	Republicans Gain Control	Republicans Hold
2004	Republicans Hold	Republicans Hold
2006	Democrats Gain Control	Democrats Gain Control
2008	Democrats Hold	Democrats Hold
2010	Democrats Hold	Republicans Gain Control
2012	Democrats Hold	Republicans Hold
2014	Republicans Gain Control	Republicans Hold
2016	Republicans Hold	Republicans Hold

Post-World II Era Midterms

1946

The Republicans take control of the House and Senate, ending 14 years of a Democratic majority in both chambers that started with Franklin D. Roosevelt’s election in 1932.

1950

The Democrats keep control of both chambers, which they took back in the 1948 general election.

1954 to 1980     

The Democrats take back the House and Senate, which they lost in the 1952 general election that saw Dwight Eisenhower elected President. The Democrats control the House and Senate in 13 consecutive elections, including six midterms.

1982

The Republicans keep control of the Senate gained in 1980, while the Democrats keep control of the House.

1986

The Democrats get back control of the Senate, while the Democrats keep control of the House.

1990

The Democrats retain control the House and Senate.

1994

The Republicans gain back the Senate and House.

1998

The Republicans keep the Senate and House for President Bill Clinton’s last two years in office.

2002

The Republicans get back the Senate and keep the House in the first congressional election after 9/11.

2006

The Democrats win back the House and gain control of the Senate thanks to two independent Senators who vote with the Democrats.

2010

In the Tea Party election, the Republicans get the House back by picking up 64 seats in the midterm election. The Democrats retain the Senate.

2014

The Republicans pick up nine Senate seats to win a total majority in Congress.

Scott Bomboy is the editor in chief of the National Constitution Center.