Tennessee furnished more soldiers for the Confederate Army than any other state, and more soldiers for the Union Army than any other Southern state. Beginning during Reconstruction, it had competitive party politics, but a Democratic takeover in the late 1880s resulted in passage of disfranchisement laws that excluded most blacks and many poor whites from voting. This sharply reduced competition in politics in the state until after passage of civil rights legislation in the mid-20th century. In the 20th century, Tennessee transitioned from an agrarian economy to a more diversified economy, aided by massive federal investment in the Tennessee Valley Authority and, in the early 1940s, the city of Oak Ridge. This city was established to house the Manhattan Project's uranium enrichment facilities, helping to build the world's first atomic bomb, which was used during World War II.

Answer this question, if possible (if impossible, reply "unanswerable"): What made Tennessee politics more competitive again in the middle of the 20th century?
civil rights legislation