Otis is a city in Rush County, Kansas, United States. As of the 2020 census, the population of the city was 296. Otis was founded in 1886…Otis is a city in Rush County, Kansas, United States. As of the 2020 census, the population of the city was 296. Otis was founded in 1886, and named for the founder's son, Otis Modderwell. The first post office in Otis was established in August 1887.