In the 1950s, Owosso was reported by a major Montgomery, Alabama, newspaper to be a sundown town, where African Americans were not allowed to live or stay overnight. The pattern of settlement and migration resulted in a majority-white city. In 1876, the city organized its fire department. Many other settlers also migrated across the Northern Tier from New York and New England. The city's first mayor was Amos Gould, a judge originally from New York. Owosso was incorporated as a city in 1859, at which time it had 1000 people. They lived on Oliver and Water streets where they operated an Underground Railroad waystation, where they provided aid and shelter for enslaved African Americans. Barnes, a physician and a judge, and Sophronia King Barnes moved to Owosso in 1842.
They were joined by Elias Comstock, who built the first permanent home in the settlement. Williams were early European-American settlers in the area. The city was named after Chief Wosso, an Ojibwe leader of the Shiawassee area. The city is mostly surrounded by Owosso Township on its west, but the two are administered autonomously. The population was 14,714 at the 2020 census. Owosso is the largest city in Shiawassee County in the U.S.
