When was control of Congress closest?
Congressional majority margins
House marginSenate margin
2025House margin 1.1%Senate margin 8.0%
Major-party seat margin (points)
Congress · sourced historical data
How close has control of Congress been? 1917–2025
The gap between the two major parties as a share of each chamber's seats.
What this chart says
The 119th House began with only a five-seat major-party gap—about 1.1% of the chamber.
How to read it
Absolute Democratic–Republican seat difference divided by the chamber total.
Important limits
- A small seat margin is not the same as the number of seats needed to change control when vacancies or other parties are present.
The data behind the view
Every plotted value.
| Year | House margin | Senate margin |
|---|---|---|
| 1917 | 0.2% | 12.5% |
| 1919 | 11.0% | 2.1% |
| 1921 | 39.1% | 22.9% |
| 1923 | 4.1% | 11.5% |
| 1925 | 14.7% | 13.5% |
| 1927 | 10.1% | 2.1% |
| 1929 | 24.4% | 17.7% |
| 1931 | 0.5% | 1.0% |
| 1933 | 45.1% | 24.0% |
| 1935 | 50.3% | 46.3% |
| 1937 | 56.6% | 63.8% |
| 1939 | 21.4% | 48.9% |
| 1941 | 24.1% | 40.0% |
| 1943 | 3.0% | 19.8% |
| 1945 | 12.6% | 19.8% |
| 1947 | 13.3% | 6.3% |
| 1949 | 21.1% | 12.5% |
| 1951 | 8.3% | 2.1% |
| 1953 | 1.8% | 1.0% |
| 1955 | 6.7% | 1.0% |
| 1957 | 6.7% | 2.1% |
| 1959 | 29.7% | 30.0% |
| 1961 | 20.9% | 28.0% |
| 1963 | 18.9% | 32.0% |
| 1965 | 35.6% | 36.0% |
| 1967 | 14.0% | 28.0% |
| 1969 | 11.7% | 14.0% |
| 1971 | 17.2% | 10.1% |
| 1973 | 11.7% | 14.1% |
| 1975 | 33.8% | 24.2% |
| 1977 | 34.3% | 23.0% |
| 1979 | 27.8% | 17.0% |
| 1981 | 11.7% | 7.0% |
| 1983 | 23.7% | 10.0% |
| 1985 | 16.6% | 6.0% |
| 1987 | 18.6% | 10.0% |
| 1989 | 19.5% | 10.0% |
| 1991 | 23.0% | 12.0% |
| 1993 | 18.9% | 14.0% |
| 1995 | 6.0% | 4.0% |
| 1997 | 4.4% | 10.0% |
| 1999 | 2.8% | 10.0% |
| 2001 | 2.1% | 0.0% |
| 2003 | 5.5% | 3.0% |
| 2005 | 6.9% | 11.0% |
| 2007 | 7.1% | 0.0% |
| 2009 | 18.2% | 16.2% |
| 2011 | 11.3% | 4.0% |
| 2013 | 7.6% | 8.0% |
| 2015 | 13.6% | 10.0% |
| 2017 | 10.8% | 4.0% |
| 2019 | 8.3% | 8.0% |
| 2021 | 2.3% | 2.0% |
| 2023 | 2.1% | 2.0% |
| 2025 | 1.1% | 8.0% |