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The "Archive of Census Related Products", located at
 
  ftp ftp.ciesin.org
  cd /pub/census
 
contains a few improvements ...
 
 
o Based on user requests, we have created thinned COUNTY and STATE files
  for the CONTIGUOUS US. These thinned files are a simple concatenation of
  the county files for the 49 contiguous USA states. Thinning the files
  has been done in 3 steps, reducing polygon points by 50% in each step.
  These "thinning levels" are indicated by the "thx" filename, where x gets
  assigned a value 1,2 or 3, indicating increasing thinning levels. (The
  filename designation "00" indicates US contiguous area, instead of FIPS
  codes).
 
  /pub/census/usa/tiger/us/original
           c00.zip     unthinned county file
           s00.zip     unthinned state file
  /pub/census/usa/tiger/us/thinned
           c00th1.zip  thinned county file
           c00th2.zip  thinned county file
           c00th3.zip  thinned county file
 
 
o 1% and 5% PUMAS (Public Use Microdata Sample Areas) COVERAGES.
  Based on a new equivalency file obtained from the Bureau of the
  Census ("pumgef"), we have regenerated the PUMA boundary files,
  This new file yields much better coverages, although problems remain,
  dramatically reducing the number of unchainable polygons.
  The coverages for 1% PUMS (bpuma) and 5% PUMS (apuma) are posted in
  unthinned and thinned formats. In addition we provide a file with
  geographic centroids for the PUMS coverages (based on UIC's genlabs
  macro).
 
  /pub/census/usa/tiger/us/original
            ap00.zip      unthinned apumas
            ap00ctrd.zip  unthinned apuma centroids
            apumas.not    apuma failure report
            bp00.zip      unthinned bpumas
            bp00ctrd.zip  unthinned bpuma centroids
            bpumas.not    bpuma failure report
  /pub/census/usa/tiger/us/thinned
            ap00th1.zip   thinned apuma file
            ap00th2.zip   thinned apuma file
            bp00th1.zip   thinned bpuma file
            bp00th2.zip   thinned bpuma file
            ap00th1.txt   apuma flushing report
            ap00th2.txt   apuma flushing report
            bp00th1.txt   bpuma flushing report
            bp00th2.txt   bpuma flushing report
 
   NOTE: The "[a/b]pumas.not" files indicate the problem areas we
   encountered. There are basically 2 main areas: LA County, CA (yet, again)
   and Baltimore County, MD. In addition PUMAS infrequently fail in the New
   England states. We are very interested to hear from local experts
   in the area on thoughts of fixing these errors (even a manual fix
   appears very doable -- please email [log in to unmask] or
   [log in to unmask] directly).
 
   NOTE2: When thinning, especially severely, "slivers" and areas of less
   than 3 points may develop. These PUMAS are flushed when writing the BNA
   files,please check the "[a/b]p00th[1/2/3].txt reports.
 
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