Centralia is a city in Nemaha County, Kansas, United States. As of the 2020 census, the population of the city was 485. Centralia was found…Centralia is a city in Nemaha County, Kansas, United States. As of the 2020 census, the population of the city was 485. Centralia was founded in 1859, one mile north of the present town. When a railroad was built through the territory in 1867, Centralia was moved to the site. Centralia was incorporated in 1882. One of the early residents of Centralia was Floyd Perry Baker, a Kansas politician and newspaper editor, who moved there with his family from Andrew County, Missouri circa 1860.