| Term | Beg. Year | End Year | Senate | Senate | House | House | |
|---|---|---|---|---|---|---|---|
| 56th | 1899 | 1900 | 60.2 | R | 52.7 | R | |
| 57th | 1901 | 1902 | 63.3 | R | 56.1 | R | |
| 58th | 1903 | 1904 | 62.9 | R | 54.4 | R | |
| 59th | 1905 | 1906 | 64.4 | R | 64.9 | R | |
| 60th | 1907 | 1908 | 66.3 | R | 57.1 | R | |
| 61st | 1909 | 1910 | 64.8 | R | 54.7 | R | |
| 62nd | 1911 | 1912 | 52.6 | R | 58.9 | D | |
| 63rd | 1913 | 1914 | 55.2 | D | 66.5 | D | Federal Reserve Act |
| 64th | 1915 | 1916 | 57.3 | D | 52.3 | D | |
| 65th | 1917 | 1918 | 53.1 | D | 50.2 | D | |
| 66th | 1919 | 1920 | 52.1 | R | 55.8 | R | |
| 67th | 1921 | 1922 | 61.5 | R | 69.1 | R | |
| 68th | 1923 | 1924 | 54.2 | R | 51.3 | R | |
| 69th | 1925 | 1926 | 54.7 | R | 57 | R | |
| 70th | 1927 | 1928 | 51.6 | R | 54.2 | R | |
| 71st | 1929 | 1930 | 55.2 | R | 61.3 | R | |
| 72nd | 1931 | 1932 | 50.5 | R | 51.4 | D | |
| 73rd | 1933 | 1934 | 62.5 | D | 72.4 | D | Glass-Steagall Act of 1933/National Housing Act |
| 74th | 1935 | 1936 | 75 | D | 73.7 | D | Social Security Act of 1935/National Labor Relations Act (“The Wagner Act”) |
| 75th | 1937 | 1938 | 77.1 | D | 76.1 | D | Fair Labor Standards Act |
| 76th | 1939 | 1940 | 70.8 | D | 59.8 | D | |
| 77th | 1941 | 1942 | 66.7 | D | 59.9 | D | |
| 78th | 1943 | 1944 | 58.3 | D | 49.8 | D | GI Bill |
| 79th | 1945 | 1946 | 55.2 | D | 55 | D | |
| 80th | 1947 | 1948 | 53.1 | R | 56.7 | R | |
| 81st | 1949 | 1950 | 55.2 | D | 60.4 | D | |
| 82nd | 1951 | 1952 | 51 | R | 53.4 | D | |
| 83rd | 1953 | 1954 | 50 | R | 50 | R | |
| 84th | 1955 | 1956 | 51 | R | 53.3 | D | Federal Aid Highway Act |
| 85th | 1957 | 1958 | 52.6 | D | 54.6 | D | National Defense Education Act/Civil Rights Act |
| 86th | 1959 | 1960 | 66 | D | 65 | D | |
| 87th | 1961 | 1962 | 62.6 | D | 59.9 | D | Trade Expansion Act/Nuclear Test Ban Treaty |
| 88th | 1963 | 1964 | 66 | D | 58.8 | D | Social Security Act of 1965/Civil Rights Act of 1964/Higher Education Act of 1965/Voting Righs Act of 1965/Amendment to Immigtation and Nationality Act |
| 89th | 1965 | 1966 | 66.7 | D | 67.8 | D | |
| 90th | 1967 | 1968 | 62 | D | 57 | D | Civil Rights Act of 1968 |
| 91st | 1969 | 1970 | 59 | D | 56.1 | D | Clean Air Act/Comprehensive Drug Abuse Prevention and Control Act |
| 92nd | 1971 | 1972 | 54 | D | 58.6 | D | Amenent to Social Security Act |
| 93rd | 1973 | 1974 | 57.6 | D | 57.1 | D | War Powers Act |
| 94th | 1975 | 1976 | 61 | D | 66 | D | |
| 95th | 1977 | 1978 | 58 | D | 66.1 | D | US Airline Deregulation |
| 96th | 1979 | 1980 | 55 | D | 63.1 | D | Economic Recovery Tax Act |
| 97th | 1981 | 1982 | 53 | R | 55.8 | D | |
| 98th | 1983 | 1984 | 55 | R | 61.5 | D | |
| 99th | 1985 | 1986 | 52 | R | 58.2 | D | |
| 100th | 1987 | 1988 | 55 | D | 58.9 | D | |
| 101st | 1989 | 1990 | 55 | D | 59.8 | D | |
| 102nd | 1991 | 1992 | 58 | D | 61.4 | D | |
| 103rd | 1993 | 1994 | 53 | D | 59.2 | D | |
| 104th | 1995 | 1996 | 53 | R | 54.3 | R | Personal Responsibility and Work Opportunity Reconciliation Act |
| 105th | 1997 | 1998 | 55 | R | 52.4 | R | |
| 106th | 1999 | 2000 | 54 | R | 51.2 | R | |
| 107th | 2001 | 2002 | 50 | R | 51.5 | R | |
| 108th | 2003 | 2004 | 51 | R | 52 | R | Emergency Quota Act |
| 109th | 2005 | 2006 | 55 | R | 53 | R | |
| 110th | 2007 | 2008 | 50.5 | D | 54.3 | D | |
| 111th | 2009 | 2010 | 58 | D | 58.8 | D | Affordable Care Act |
| 112th | 2011 | 2012 | 53 | D | 55.7 | R | |
| 113th | 2013 | 2014 | 55 | D | 53.8 | R | |
| 114th | 2015 | 2016 | 54 | R | 56.8 | R | |
| 115th | 2017 | 2018 | 50.5 | R | 54.6 | R | |
| 116th | 2019 | 2020 | 52 | R | 54.2 | D | |
| 117th | 2021 | 2022 | 50 | D | 50.9 | D | |
| 118th | 2023 | 2024 | 51 | D | 50.9 | R |