The Market Revolution had profound changes for American society. The United States began to improve its infrastructure through national roads and canals. The United States also adapted to steam technology, and businessmen created railroad lines and steamboats and made large profits. As more Americans moved west, the United States earned a reputation as being a leading agricultural producer. John Deere created the steel plow, which cut the rich heavy soils of the Great Plains easier than previous models. Eli Whitney's development of the cotton gin in 1793 greatly helped cotton production in the South and led to the explosion of the slave industry. This also helped make slavery one of the key issues of the day. Eli Whitney also developed interchangeable parts, which made goods easier to mass produce and fix. Immigrants flocked to cities in the Northeast, and the region soon employed women and children in textile mills.
Politically, the United States imposed tariffs on foreign goods in order to help American manufacturing. When South Carolina decided that it would not pay the tariff, it threatened to leave the Union and was only held in the Union when Andrew Jackson threatened to use force to keep the state in the Union. Henry Clay sought to make the United States more self-sufficient through his American System by using increased tariffs and a National Bank to pay for internal improvements. He was able to use his strategy to become a presidential candidate. The Democrats at the time saw federally funded internal improvements and a National Bank as a threat against state sovereignty.