In the early days, Chicago was inhabited by Algonquian people. With the opening of the Illinois and Michigan Canal - that runs down to the Gulf of Mexico - and the first rail line to Chicago, the city started to become the national transportation hub with road, rail, water and, air connections. Also, Chicago sits in the center of the most fertile agricultural areas of the United States. Because of all those factors, Chicago grew quickly - in less than 20 years the population grew from 4 thousand inhabitants to 169 thousand.