For directions on reading the variable description see Data Dictionary Introduction.

Availability: 
 

1850	1860	1870	1880	1900	1910	1920	1940	1950	1960	1970	1980	1990
											S,M

Universe: 
Households and group quarters in State and Metro samples. 

Description/Comparability: 
CNTYGP98 is an unrecoded variable that identifies the household's 1980 county group of enumeration. It is state-dependent; it must be read in conjunction with state codes, STATEICP and STATEFIP. 

1980 county groups are (usually) contiguous areas with a combined population of 100,000+ residents; they may consist of actual county groups, but they may also be single counties, single cities, or other census-designated places (separate or combined) meeting the 100,000+ population criterion. The State sample individually identifies most counties with 100,000+ residents and groups most other counties into "reasonable analytic units," often as defined by state planning agencies; none of these county groups cross state lines. The Metro sample county groups allow for the identification of most Standard Metropolitan Statistical Areas with 100,000+ residents, and they frequently cross state lines in the process. 

Though they have different boundaries, 1980 county groups are similar in conception to 1970 county groups (CNTYGP97) and 1990 Public Use Microdata Areas (PUMA). 

Codes: 
The contents of the 1980 county groups are detailed in machine-readable files (cg98met and cg98stat). See "Geographic Tools" Volume 2: User’s Guide Supplement for the original 1980 PUMS maps and a discussion of these files.