The balance of power in the United States government has changed many times since 1857. Control has shifted between Democrats and Republicans in the House, Senate, and White House.
When the president’s party controls both chambers of Congress, the country has a unified government. When another party controls at least one chamber, the government is considered divided.
Since the modern party system began, the United States has experienced 48 periods of unified government. Democrats controlled 23 of those periods, while Republicans controlled 25.
Quick Facts
| Detail | Information |
|---|---|
| Period Covered | 1857 to 2027 |
| Political Parties | Democratic Party and Republican Party |
| Unified Governments | 48 |
| Democratic Unified Governments | 23 |
| Republican Unified Governments | 25 |
| Institutions Covered | House of Representatives, Senate and Presidency |
| Latest Congress | 119th Congress, 2025 to 2027 |
| Latest Party Government | Unified Republican Government |
Main Political Changes Since 1857
The 35th Congress began in 1857 with Democrats controlling both the House and Senate. Democrat James Buchanan also held the presidency. This created a unified Democratic government.
Political control changed quickly during the following years. By the 36th Congress, Republicans controlled the House while Democrats controlled the Senate and White House.
The 37th and 38th Congresses brought a Republican government under President Abraham Lincoln. Republicans controlled both chambers of Congress during this period.
The Civil War period also produced an unusual change. Lincoln died in April 1865, and Vice President Andrew Johnson became president. Johnson was a Democrat, while Republicans continued to control Congress.
Republican Control in the Late 1800s
Republicans held strong control during several Congresses after the Civil War. Ulysses S. Grant served as president while Republicans controlled both chambers from the 41st through the 43rd Congresses.
The balance changed during the following years. Democrats controlled the House in several Congresses while Republicans controlled the Senate and White House.
Republican President James Garfield also died during the 47th Congress. Vice President Chester Arthur then became president. Both men belonged to the Republican Party, so the party control of the White House did not change.
Political Shifts in the Early 1900s
Republicans dominated the federal government during much of the early 20th century.
William McKinley served as president while Republicans controlled both chambers. After McKinley died in 1901, Theodore Roosevelt became president. Roosevelt also belonged to the Republican Party.
Republicans continued to control the House, Senate, and presidency through several Congresses under Roosevelt and William Howard Taft.
Democrats later gained control of the House. However, Republicans still held the Senate and presidency under Taft. This created a divided government.
Democrats Gain Strong Control
Franklin D. Roosevelt brought a long period of Democratic control beginning in 1933.
Democrats controlled both chambers of Congress throughout his presidency for many years. Roosevelt died in April 1945, and Vice President Harry Truman became president.
Because Truman was also a Democrat, the party continued to control the federal government.
Republicans briefly gained control of Congress in the 80th Congress. Truman remained president, creating a divided government.
Republican Dwight D. Eisenhower became president in 1953. Republicans controlled both chambers during the 83rd Congress.
Democrats then regained control of both chambers. Eisenhower remained president, producing divided government during several Congresses.
John F. Kennedy restored unified Democratic control in 1961. After Kennedy’s assassination in 1963, Vice President Lyndon B. Johnson became president.
Democrats continued to control both chambers during Johnson’s presidency.
From Nixon to ReaganFrom Nixon to Reagan
Richard Nixon became president in 1969, but Democrats controlled both chambers of Congress. The same basic pattern continued through the Nixon and Gerald Ford years.
Democrat Jimmy Carter later became president in 1977. Democrats also controlled both chambers during the 95th and 96th Congresses.
Republican Ronald Reagan entered the White House in 1981. Democrats controlled the House, while Republicans controlled the Senate. This created divided government.
That arrangement continued through several Congresses. Democrats later regained control of the Senate while Reagan remained president.
Obama, Trump and Biden
Bill Clinton became president in 1993. Democrats controlled both chambers during the 103rd Congress.
Republicans took control of the House and Senate in 1995. Clinton remained president, creating divided government for the rest of his presidency.
George W. Bush entered the White House in 2001. Republicans initially controlled Congress, although Senate control changed several times during the 107th Congress.
Republicans then held both chambers during the 108th and 109th Congresses. This gave Bush a unified government.
Democrats took control of both chambers in 2007. Bush remained president, producing divided government.
Current Party Government in the Chart
The 119th Congress began in 2025. Republicans controlled both the House and Senate, while Donald Trump returned to the presidency.
The chart therefore classifies the 119th Congress as a unified Republican government.
This period is the latest entry in the historical data provided in the chart. The 119th Congress covers 2025 through 2027.
Party Government Since 1857
| Party | Unified Governments |
|---|---|
| Democratic | 23 |
| Republican | 25 |
| Total | 48 |
What the Historical Record Shows
The history since 1857 shows that political control regularly moves between the two major parties.
Democrats have controlled periods of unified government under presidents such as Franklin D. Roosevelt, Woodrow Wilson, Lyndon B. Johnson, Bill Clinton, Barack Obama and Joe Biden.
Republicans have also held unified government during several important periods. These include the administrations of Abraham Lincoln, Ulysses S. Grant, William McKinley, Theodore Roosevelt, Dwight D. Eisenhower, Ronald Reagan and Donald Trump.
The balance between Congress and the presidency remains one of the most important features of American politics.
US Party Government Changes Since 1857
The party government record since 1857 shows how frequently political power has shifted in the United States.
Some periods brought one party control of the House, Senate and White House. Other periods produced divided government.
The latest entry in the chart, the 119th Congress, shows Republicans controlling both chambers while Donald Trump serves as president.
