[Geowanking] Re: neighborhood database?
wkearney99 at hotmail.com
Mon Sep 17 16:18:28 PDT 2007
Anselm Hook wrote:
> The colored polygons are neighborhoods and the larger red outlined
> areas are districts. Not sure what the smaller red polygons are;
> perhaps lava.
The legend calls them Census Block Groups.
STFW enlightens further:
*Census Blocks:* Blocks are the smallest entity for which the Census
Bureau collects and tabulates census information (SF 1 only). There are
about 8.5 million blocks nationwide.
*Block Groups: *Block Groups are a combination of census blocks and are
also a subdivision of census tracts. Block groups generally contain
between 600 and 3000 people and are made up of on average 40 census
blocks. There are about 211,000 block groups nationwide.
*Census Tracts: *Tracts are a small, relatively permanent statistical
subdivision of a county delineated by a local committee of census data
users for the purpose of presenting census data. Census tract boundaries
normally follow visible features, but may follow governmental unit
boundaries and other non-visible features, and they always nest within
counties. Census tracts are designed to be relatively homogenous units
with respect to population characteristics, economic status, and living
conditions at the time the users established them. They usually contain
1,500 to 8,000 people and are made up of on average about four block
groups. There are about 66,000 tracts nationwide.
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