Seymour is a city in Jackson County, Indiana, United States. Its population was 21,569 at the 2020 census. The city is noted for its location at the intersection of two major north–south and east–west railroads, which cross each other in the downtown area. The north–south line (the Jeffersonville, Madison and Indianapolis Railroad) was built in the 1840s and connected Indianapolis to the Ohio River at Jeffersonville. In 1852, Captain Meedy Shields persuaded Hezekiah Cook Seymour into building the eastwest railroad (the Ohio and Mississippi Railroad) through his land, and in return named the city in Seymour's honor. The firsts settlers arrived in the spring of 1853. The companies Aisin USA and Rose Acre Farms are headquartered in Seymour, and Cummins operates a plant in the area. The city is also home to the 2nd largest high school gymnasium in the United States by seating capacity. History 19th Century Seymour was laid out and plated on April 27, 1852, near the 1809 Indian Treaty Corner and approximately two miles south of the village of Rockford, Indiana; the terminus of the north-south railroad before the opening of the purchase of 1828 and the construction of the railbridge over the White River. During the latter 1840's, a north–south railroad connecting the Ohio River at Jeffersonville with Indianapolis was built crossing the Shields’ farm. In 1852, an east–west railroad was being surveyed through Jackson County and Meedy Shields persuaded the Ohio and Mississippi Rail Road to run through his property. In exchange for this favor, he agreed to name the town after the railroad's civil engineer, Henry C. Seymour, although some sources mention J. Seymour, who was the surveyor. Seymour was derisively referred to as a "mule crossing" because its slow initial development and lack of interest from the railroad companies. The town did not see significant development until the state legislature, led by the efforts of Indiana State Senator, Meedy Shields, passed a law requiring all trains to stop at railroad-railroad intersections. By increasing safety statewide in a time before widespread semaphore use, it increased the value of land around such intersections and made them safer for warehousing. In 1858, Blish Mill opened as the first mill in town. By 1881, Seymour would have three mills within the city limits. The large grain tower still stands near the north-south and east-west railroad intersection and the center of town. Seymour was once a stop