Included in this file for each wave of the study are the Beale Rural-Urban Code and the Size of Largest City in the County.

Also available in the County Identifiers File from 1968-1993 is a collection of Census variables pertaining to county and state level information. Variables include: County Unemployment Rate; Unskilled Wage Rate; Unskilled Labor Supply; Per Student Public School County Expenditures; and State Minimum Wage. To see the specific variables available for each year, please see the variable list.
  The file also includes the identification codes necessary to link county data from the PSID in each year to contextual data from secondary sources such as the Census. Geocoding has been conducted using five different Censuses. Addresses from 1968-1985 were geocoded to 1970 and 1980 census identifiers; those from 1968-1999 were geocoded to the 1990 census identifiers; those from 1968-2009 were geocoded to the 2000 census identifiers; and starting with the 2011 wave, address information has been geocoded to the 2010 census identifiers.