Haven is a city in Reno County, Kansas, United States. As of the 2020 census, the population of the city was 1,170. Haven was laid out in 1…Haven is a city in Reno County, Kansas, United States. As of the 2020 census, the population of the city was 1,170. Haven was laid out in 1886, and incorporated as a city in 1901. The first post office in Haven was established in 1873.