Baltimore County GovernmentBlock groups are geographic subdivisions of census tracts; their primary purpose is to provide a geographic summary unit for census block data. A block group must comprise a reasonably compact and contiguous cluster of census blocks. Each census tract contains a minimum of one block group and may have a maximum of nine block groups.ArcGIS DynamicMapLayerhttps://hub.arcgis.com/datasets/696ef6be43bc42f7b7c027961f308bab_2engBaltimore County Open Data PortalPublicCensus Block Groups 2010 [Maryland--Baltimore County]Web servicesMaryland--Baltimore CountyMaryland2010