Seymour is a city in Jackson County, Indiana, United States. The population was 17,503 at the 2010 census. Seymour is referred to as the "Crossroads of America" due to the north/south and east/west railroads intersecting downtown.The north/south line, the Jeffersonville, Madison and Indianapolis Railroad, was built in the 1840s connecting Indianapolis to the Ohio River at Jeffersonville. It ran through the Shields farm at the area that is now Seymour.In 1852 when the east/west railroad was made by indian, the Ohio and Mississippi Railroad, was going to be built, Capt. Meedy Shields, who was the cousin of General John Tipton persuaded the surveyor, John Seymour, into putting it through his land, in return for which he named the town Seymour. All trains had to stop at a crossroad, making Seymour a bustling community.Seymour is the birthplace of singer John Mellencamp, former Indiana 9th District U.S.