In 1840 , Chicago was the ninety-second most populous city in the United States . Its population grew so rapidly that twenty years later , it was the ninth most populous city in the country . In the pivotal year of 1848 , Chicago saw the completion of the Illinois and Michigan Canal , its first steam locomotives , the introduction of steam-powered grain elevators , the arrival of the telegraph , and the founding of the Chicago Board of Trade . By 1870 Chicago had grown to become the nation 's second largest city , and one of the largest cities in the world . By 1857 Chicago was the largest city in what was then called the Northwest . In a period of twenty years Chicago grew from 4,000 people to over 90,000 . Chicago surpassed St. Louis and Cincinnati as the major city in the West . It gained political notice as the home of Stephen Douglas , the 1860 presidential nominee of the Northern Democrats . The 1860 Republican National Convention in Chicago nominated home-state candidate Abraham Lincoln . The city government and voluntary societies gave generous support to soldiers during the war
1860 Republican National Convention
1860 Republican National Convention
History of Chicago