Seneca is located on the Illinois River, which connects the Mississippi River to Lake Michigan. Seneca hosts three marinas on the south side of the Illinois River, as well as a public boat launch on the north side of the Illinois River. Seneca is rich with history with the Illinois and Michigan Canal running through the center of the city's downtown area. The business community continues to change as the small businesses and merchants unite to improve the existing business community and attract new businesses.