The Atlantic and Pacific Railroad reached Neosho in 1870. The A& P eventually became the San Francisco and St Louis railroad. In 1878, Neosho was incorporated and the first permanent courthouse was constructed in the center of the town square. In 1887 the Kansas City-Fort Smith and Southern Railroad entered Neosho. The KCFS& S served the Neosho National Fish Hatchery, the oldest Federal Fish Hatchery still operating today, which was built the following year. This railroad was eventually sold to the Kansas City Southern Railroad which still operates and runs through Neosho today.