2010 Block Groupsfrom the Michigan Geographic Framework (MGF) base map.Block groups (BG's) are combinations of census blocks within a census tract or BNA that share the same first digit in their identifying numbers. For example, BG 3 within a particular census tract comprises all blocks numbered between 301 and 399. A census tract or BNA contains a maximum of nine BGs. BG2010 consists of the 6 digit tract number followed by the 1 digit block group number.More Metadata