This dataset provides vacant housing unit estimates by vacancy status for State of Iowa, individual Iowa counties, incorporated places (i.e., cities) and census tracts within Iowa. The five-year data are collected over a period of 60 months for all geographic areas. Estimates are more reliable for smaller areas (under 20,000 population). Data is from the U.S. Census Bureau, American Community Survey, Five Year Estimates, Table B25004. Values should not be aggregated across multiple variables, geographies, and years. Also, comparisons should not be made between overlapping data collection periods (e.g. 2012-2016 and 2013-2017).
https://www.census.gov/programs-surveys/acs