Two 19th-century midterm elections offer a reminder that significant shifts in congressional power, like those expected in the 2026 midterms, can signal long-term changes in American politics. The Democratic Party is currently seen as having an advantage in the upcoming elections, potentially becoming the majority party in one or both chambers of Congress. However, the exact size of their victory remains uncertain. Historically, the size of a party’s majority has had major consequences. In the late 1800s, two major midterm election results marked the beginning of important political eras. In 1874, during the second term of Republican President Ulysses S. Grant, the Democrats won over 90 new seats in the House of Representatives. This ended Republican dominance in Congress, which had begun with Abraham Lincoln’s election in 1860. The shift also marked the end of Reconstruction, a period of federal efforts to rebuild the South after the Civil War. White Southerners regained control of state governments, and the Democratic Party, now in power, used violence and intimidation to suppress Black voters. This set the stage for a long period of Democratic control in the South and in Congress. For the next two decades, the political landscape was highly competitive, with neither party maintaining a clear majority. No president between Grant and William McKinley’s 1896 election won a majority of the popular vote, and no president had full control of both Congress and the White House for more than two years. This period of political stalemate limited the ability of any administration to enact major policies. McKinley’s victory in 1896 marked the beginning of a new era of Republican dominance that lasted for decades. His successor, Theodore Roosevelt, helped define the modern presidency with expanded executive power and direct communication with the public. This shift, known in political science as a “realignment,” had its roots in the 1894 midterm elections, when President Grover Cleveland suffered a historic defeat. His Democratic Party lost over 100 House seats to Republicans and third-party candidates, signaling the start of a new political era. While major shifts like those in 1874 and 1894 are rare, smaller midterm losses have often forced sitting presidents to adjust their strategies. Presidents such as Harry Truman, Lyndon Johnson, and Barack Obama faced significant losses in the House and responded by either changing their approach or losing re-election. These “wake-up call” elections are more common and are likely to occur in 2026. The 2026 midterms are not expected to produce the dramatic changes seen in the 19th century, but they could still have major consequences. In a closely divided nation with gerrymandered districts, even a small shift in House seats could change the balance of power. Democrats may not need a large swing to regain the majority; flipping a few key districts could be enough. If this happens, it could lead to a new political direction or set the stage for future elections. Regardless of the outcome, the midterms are likely to shape American politics in meaningful ways.