_dta:
  1.  counties1990 set up by Jean Roth , jroth@nber.org , 29 Mar 2016
  2.  Source Page: http://www.census.gov/geo/maps-data/data/gazetteer1990.html
  3.  Source File URL: http://www2.census.gov/geo/docs/maps-data/data/gazetteer/counties.zip
  4.  Source File: counties.txt
  5.  by Jean Roth , jroth@nber.org , 29 Mar 2016
  6.  Census Gazetteer County file
  7.  Unique identifier is county
  8.  Distances between County that are within 100 miles

  obs:       141,716                          
 vars:             4                          29 Mar 2016 15:54
 size:     8,644,676                          (_dta has notes)
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              storage   display    value
variable name   type    format     label      variable label
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county1         str5    %9s                   FIPS County
mi_to_county    double  %10.0g                Distance between Counties that are within 100 miles
county2         str5    %9s                   FIPS County
name            str43   %43s                  County Name
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Sorted by: county1  mi_to_county  county2