The Third Party System, a term of periodization used by some historians and political scientists to describe a period in American political history from about 1854 to the mid-1890s, features profound developments in issues of nationalism, modernization, and race.

This period is defined by its contrast with the eras of the Second Party System and the Fourth Party System.

It is dominated by the new Republican Party, which claims success in saving the Union, abolishing slavery and enfranchising the freedmen, while adopting many Whiggish modernization programs such as national banks, railroads, high tariffs, homesteads and aid to land grant colleges.

While most elections from 1874 through 1892 are extremely close, the opposition Democrats win only the 1856, 1884 and 1892 presidential elections, though from 1874 to 1892 the party often controls the United States House of Representatives.

The northern and western states are largely Republican, save for closely balanced New York and Indiana.

After 1874, the Democrats takecontrol of the "Solid South."