Degree of Detail in Place of Work and Migration in 1990 PUMS File

"Unlike current residence, the PUMAs for migration and place-of-work data are defined only to the whole county, county equivalent, or place level for PUMS. Therefore, it is not possible to tabulate either migration or place-of-work to the 'group of census tracts level.'"

Source: Census of Population and Housing, 1990: Public Use Microdata Sample U.S. Technical Documentation, page C-5. / prepared by the Bureau of the Census. Washington: The Bureau, 1992.

For the place of residence variable, PUMA, the detail is down to individual PUMAs, which represent about 100,000 people. For instance, respondents who live in Detroit city would be represented by one of the following PUMAs:

03301
03302
03303
03304
03305
03306
03307
03308

However, a respondent that lived in Livonia city, Michigan and works in Detroit city, Michigan would be represented in the PUMS data as follows:

     STATE   PUMA   POWSTATE   POWPUMA
       26    03500     26       03300

The place of work PUMA (03300) represents 1,027,974 people, instead of the approximately 100,000 people that are in each place of residence PUMA.

However, if a person migrates from or works in a county of less than 200,000 and the county is not sub-divided into multiple PUMAs, the level of detail on POWPUMA and/or MIGPUMA is at the same level as the place of residence PUMA. For instance, if a person lived in Oceola County, Michigan (PUMA = 01100) and worked in Isabella County, Michigan (POWPUMA = 01000), the population sizes represented by each of these variables is about the same:

      PUMA     POWPUMA         Population size
     01000      01000              118,558
     01100      01100              205,427

See the following for identification of PUMAs on a state by state basis.


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