🚀 go-pugleaf

On Wed, 30 Aug 1995 11:17:59 -0400 H. Mark Keintz said:
>We have data covering all states of the U.S. that includes address
>information for each observation in our file.  We want to determine a county
>for each address in our data set.
>
>Yes, our addresses include ZIP codes, and yes, I have located the zipcnty
>SAS program kept at CIESIN (thanks to John Blodgett and Henk Meij).  But,
>as John's explanatory memo points out, 13% of all ZIP code areas cross
>county borders.  For addresses in those ZIP codes, we need a way to
>determine a county knowing other address information (address, street or
>road, place).  Where can I look for such information?
>
>
>thanks,
>mark
>
>
>Mark Keintz                            University of Pennsylvania / 6298
>mark_keintz@pop.upenn.edu              Population Studies Center
>phone:  215/898-6713                   3718 Locust Walk
>fax:    215/898-2124                   Philadelphia, PA 19104-6298
There are a growing number of sources for address info to handle this.
Depends on how big the job is, is it a 1-time thing or something you want
to totally automate and run all the time.  The USPS puts out address
files updated at least quarterly, I believe, with complete address range
and ZIP-county info.  I haven't subscribed for a couple of yrs but I
think its around $800 a year.  No software, just address files.  Many
of the commercial sources use these as their base data.
   The Census Bureau has released the TIGER/Census Tract Street Index
Guides (be sure to get Version 2!).  Its 5 or 6 cd-roms to cover the
u.s. and it has a nice "go"-type program to let you manually look up an
address and get a series of geocodes including county, tract and place.
You start by specifying a state.  The files are in .dbf format and could
be pretty easily read and stored.  You could probably build a file that
would relate street name-ZIP to county.  Requires some programming, of
course.  You could easily build a table of ZIP-county correspondences
off the CTSI files.  We did some weighted freqs and determined that 93%
of the population lives in ZIP codes that are entirely in one county.
So you should only have to really deal with about 7% of your addresses
(actually, more than that if you use the CTSI because of the problem
of new ZIPs not on the Bureau's files - they are 5 yrs old).
     The good news is that almost all new ZIPs are
in metro areas and metro ZIPs are much less likely to cross county
boundaries.  But you'd still need to do some research on these new codes.

   John Blodgett
   Urban Information Center / Office of Computing
   University of Missouri - St. Louis      8001 Natural Bridge Rd.
   St. Louis, Mo 63121-4499     Phone: (314) 516-6014/6000 FAX: 516-6007


P.S. If you'd like more info about the Bureau's CTSI cd-rom products
 and have access to WWW you can get all the info you want and even place
 your order over the net.  Connect to www.census.gov, select Market Place
 --cdrom products--TIGER Line & related products--Census Tract Street
 Index Version 2.  You'll discover it comes on 6 cd-roms for $400.  They
 should also be available at your local government documents library.