Shelbyville is a city located adjacent to Springfield. Shelbyville and Springfield are treated in the series as twin cities, though with an intense rivalry between the two. The city of Shelbyville was founded by Shelbyville Manhattan in 1796, who held the belief that people should be allowed to marry their cousins, a practice disallowed by fellow explorer and founder of Springfield, Jebediah Springfield. As a result of this disagreement, the two founders and their party split into separate groups, and went their own ways; since that time, the populaces of Springfield and Shelbyville have held a strong rivalry.