This field is provided for coding the block group of patient’s residence at time of diagnosis, as defined by the 1970, 1980, or 1990 Census.
Formerly CensusBlockGroup 70/80/90.
A block group is a subdivision of a census tract or block numbering area (BNA). Not all of the United States was described by a census block group or BNA prior to the 2000 Census, but for areas assigned to block groups or BNAs, the Census Bureau published detailed population and socioeconomic data. Block groups thus offer a high level of specificity for geographical and socioeconomic analyses, where available.
A block group has no meaning in the absence of a census tract. Refer to Census Tr Cert 1970/80/90 [364] to ascertain the basis of assignment of Census Block Grp 1970-90 [368]. Refer to Census Cod Sys 1970/80/90 [120] to ascertain the decade of reference.