In the eighteen fifties, Stephen A. Douglas, a United States Senator from Illinois and chairman of the Senate Committee on Territories, worked to secure construction of a transcontinental railroad and favored a northern route that would benefit Illinois and Chicago. Because investors were reluctant to support a railroad where state governments had not already been established, he sought to speed the admission of Kansas and Nebraska as states. Under the Missouri Compromise, both Kansas and Nebraska were to remain free states, but Kansas was being settled mostly by pro-slavery advocates. Douglas argued for Popular Sovereignty, allowing the people of a state or territory to decide whether it would be free or slave rather than leaving that decision to Congress. As it became clear that Kansas might be admitted as a slave state, breaking the Missouri Compromise, abolitionists and anti-Nebraska Democrats opposed the legislation, but Douglas prevailed and the Kansas-Nebraska Act was passed. Its repeal of the Missouri Compromise drew Abraham Lincoln out of private law practice and back into politics, setting the stage for his challenge to Douglas's reelection in eighteen fifty-eight.