Map Flint - Feature Service layer(s) : ACS5YR 2013-2017 estimates for Sanilac County, Michigan, USA by county subdivision of Median Year Structure Built. Note: Layer(s) not initially visible and must be turned on. This feature layer is an American Community Survey (ACS) estimate (U.S. Census Bureau) that is derived from the National Historical Geographic Information System (NHGIS) and has been customized for various Map Flint analyses and projects pertaining to the City of Flint, Genesee County, Michigan U.S.A. and other surrounding counties - e.g., counties and communities in the greater Flint vicinity that also overlap with the mission of the University of Michigan-Flint EDA University Center for Community and Economic Development. All NHGiS layers in Map Flint projects maintain the uniquely-valued GISJOIN geographic ID assigned by the NHGIS in order to work with multiple data sets. For more information, visit https://mapflint.org