[gis_info] Posting for gis info - Tiger 08

[Richard Lycan]

The TIGER files for all of Oregon (and the US) now are available on the
Census Bureau web-site. In 2002 the Census Bureau awarded a contract for
$200 million to Harris Corporation for the "Master Address
File/Topologically Integrated Geographic Encoding and Referencing Accuracy
Improvement Project" (http://www.census.gov/geo/mod/maftiger.html). This
work is now complete and is included in the 2008 Tiger file release, now
available on the Census Bureau website
(http://www.census.gov/geo/www/tiger/tgrshp2008/tgrshp2008.html). You can
download from a selection tool or you can download from the Tiger FTP site.
You will need to look at the documentation
(http://www.census.gov/geo/www/tiger/tgrshp2008/TGRSHP08.pdf) as there are a
variety of shape and attribute files for each geography. Geography's can be
downloaded for the nation, states, counties or American Indian areas. All of
these data are provided as shape files - there is no need to use an import
or conversion program.

 

The polygon files describe all of the geographies for which census data is
tabulated down to the census block level and including many special
geographies such as TAZ's and school districts. 

 

There also is a line or "edge" file showing roads, water features, shopping
areas, and many other types of features. This file also has fields for left
and right, high and low address ranges but not all segments have the address
range data. There are attribute files that can be related to the edges. One
is the complete left and right geography for each edge - which census block
is on the left, and which is on the right. These relations can be used to
summarize geo-coded address data to census geographies such as blocks or zip
code areas. The detailed feature class codes, found in an appendix to the
documentation, can be used to identify different classes of roads, water
features, and landmarks by joining it to the edge file, or contact me if you
wish a copy of the feature class detail in database format. 

 

Most of the enhanced accuracy results from the data provided by Oregon local
governments. The completeness of the street network, the place name
inclusion and accuracy, and the completeness of the address ranges vary from
county to county.

 

 

 

 

Richard Lycan

Professor Emeritus of Geography and Urban Studies

Population Research Center

Portland State University

Portland, OR 97207-0751

503-725-5158

lycand at pdx.edu

 

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