In which election was the outcome contested by both the Democratic and Republican parties?

The election of 1876 is notable for being one of the most disputed elections in U.S. history, leading to a significant controversy between the Democratic and Republican parties. In this election, Republican candidate Rutherford B. Hayes and Democratic candidate Samuel J. Tilden both claimed victory. Tilden won the popular vote and had a majority of electoral votes but fell just one short of the necessary number to secure the presidency. Disputes arose over the results in several states, with both parties asserting that they had legitimate claims to the electoral votes.

To resolve the impasse, Congress created a special electoral commission that ultimately decided in favor of Hayes by a slim margin. This decision was highly contentious and resulted in significant political ramifications, including the Compromise of 1877, which effectively ended Reconstruction in exchange for resolving the election dispute.

In contrast, the elections of 1884, 1896, and 1900 did not experience such a high level of contestation and conflict regarding the electoral outcomes. These elections were more straightforward in terms of results, leading to clearer victories for the respective candidates. Therefore, the election of 1876 stands out as a key moment of electoral dispute that shaped the political landscape of the United States.