Re: [CTPP] 2000 Census Traffic Analysis Zones

Dmitry: When you use the GIS shape file from http://www.census.gov/geo/www/cob/bdy_files.html you<http://www.census.gov/geo/www/cob/bdy_files.html%20you> are using a "generalized GIS file." The limitations of these files are listed on the CB website as follows: "The generalized files have a much smaller file size than the original file extraction from the Census Bureau's TIGER database, resulting in faster download and processing times. Limitations Because of coordinate thinning: 1. Cartographic boundary files should not be used for geocoding; 2. Some offshore, redundant, zero population and housing land areas may be absent from the files; 3. Cartographic Boundary files are not necessarily vertically integrated with previous boundary file sets." For smaller geographies such as TAZs, you are better off using a detailed shape file/Any other GIS file derived from TIGER directly. Thanks Nanda From: ctpp-news-bounces(a)chrispy.net [mailto:ctpp-news-bounces@chrispy.net] On Behalf Of Messen, Dmitry Sent: Wednesday, February 22, 2012 8:45 PM To: ctpp-news(a)chrispy.net Subject: [CTPP] 2000 Census Traffic Analysis Zones Would anybody know what the deal was with the 2000 Census Traffic Analysis Zones? I am working with CTPP 2000 Table 3 data. To do some spatial analysis, I turned to census boundary files for traffic analysis zones (http://www.census.gov/geo/www/cob/bdy_files.html). I quickly realized that 63 out 2639 zones for the Houston region are represented by 2+ non-adjacent polygons. Does this happen in other regions as well? Was this delineation done purposefully or perhaps these are simply errors stemming from TIGERLine 2000? Any input will be much appreciated. Thank you. Dmitry Messen H-GAC dmessen@h-gac.com<mailto:dmessen@h-gac.com>