Senator Stephen A. Douglas was an American politician from Illinois who served in the U.S. Senate from 1847 to 1861. He was a member of the Democratic Party and is best known for his debates with Abraham Lincoln during the 1858 Illinois Senate race. Douglas advocated for popular sovereignty, allowing territories to decide on the legality of slavery. Douglas played a significant role in the passage of the Kansas-Nebraska Act in 1854, which created the territories of Kansas and Nebraska and allowed settlers to determine whether they would permit slavery. His actions contributed to the growing tensions leading up to the American Civil War.