This is a MD iMAP hosted service layer. Find more information at http://imap.maryland.gov. Block Groups (BGs) are defined before tabulation block delineation and numbering - but are clusters of blocks within the same census tract that have the same first digit of their 4-digit census block number from the same decennial census. Census 2010 BGs generally contained between 600 and 3 - 000 people - with an optimum size of 1 - 500 people. Most BGs were delineated by local participants in the Census Bureau's Participant Statistical Areas Program (PSAP). Last Updated: Feature Service Layer Link: https://mdgeodata.md.gov/imap/rest/services/Demographics/MD_CensusBoundaries/MapServer ADDITIONAL LICENSE TERMS: The Spatial Data and the information therein (collectively "the Data") is provided "as is" without warranty of any kind either expressed implied or statutory. The user assumes the entire risk as to quality and performance of the Data. No guarantee of accuracy is granted nor is any responsibility for reliance thereon assumed. In no event shall the State of Maryland be liable for direct indirect incidental consequential or special damages of any kind. The State of Maryland does not accept liability for any damages or misrepresentation caused by inaccuracies in the Data or as a result to changes to the Data nor is there responsibility assumed to maintain the Data in any manner or form. The Data can be freely distributed as long as the metadata entry is not modified or deleted. Any data derived from the Data must acknowledge the State of Maryland in the metadata.