Slater is a city in Story County, Iowa, United States. The population was 1,543 at the time of the 2020 census. There has been a post office i…Slater is a city in Story County, Iowa, United States. The population was 1,543 at the time of the 2020 census. There has been a post office in Slater since 1887. The city was named for Michael Slater, the original owner of the town site.