Florence is a city in Marion County, Kansas, United States. As of the 2020 census, the population of the city was 394. The city was named after …Florence is a city in Marion County, Kansas, United States. As of the 2020 census, the population of the city was 394. The city was named after the daughter of the third Governor of Kansas Samuel J. Crawford. It is located at the intersection of U.S. Route 50 and U.S. Route 77 highways.