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| Subject: | Re: [gislist] Census Boundary Files Origin |
| Date: |
10/27/2003 06:45:00 AM |
| From: |
charles.e.dingman .. census.gov |
|
|
The message bounced from the list server, so I reset options to try to =
get
Lotus Notes to send plain text.
Charles Dingman, Geographer/301-763-1120
Rm 425, WP-1, Geography Division
US Census, 4700 Silver Hill Rd Stop 7400
Washington, DC 20233-7400
__________________
I am not sure what "populated places" are meant, because I don't see
anything called that=A0in Census products.=A0 The data sets Caliper put=
s
together include census places, legal and statistical, as polygons, fro=
m
Census sources, along with point locations of "populated places" from U=
SGS
sources, the GNIS I believe, a data base of geographic names.=A0 The bo=
undary
files Census distributes=A0come from the detailed geographic data base =
used
in the Census operations and tabulations, TIGER, as do the TIGER/Line
Files.=A0 Places in that context mean CDPs (statistical areas) and
incorporated places (legal areas).
Incorporated places and other legal areas come from the Boundary and
Annexation Survey returned by local officials as the boundaries in effe=
ct
Jan. 1 of the census year.=A0 The legal limits do not have to follow an=
y
visible feature, and are always made census block boundaries.=A0 CDPs a=
re
defined before the census in cooperation with local officials, often
planning boards, and have to follow visible features, with a few except=
ions
such as short extensions of streets into RR or river features, and
point-to-point lines between physical features.=A0 They are defined to
represent what are locally regarded as "places" but are not legally
incorporated.=A0 The CDP boundaries mostly follow=A0the kind of feature=
that
would be held as a block boundary in any case, and as tabulation areas =
for
the census, have to be made census block boundaries because census bloc=
ks
have to add up to any area that is to be tabulated.
You will find reference material and glossaries at
http://www.census.gov/geo/www/reference.html
Charles=A0Dingman,=A0Geographer/301-763-1120
Rm=A0425,=A0WP-1,=A0Geography=A0Division
US=A0Census,=A04700=A0Silver=A0Hill=A0Rd=A0Stop=A07400
Washington,=A0DC=A020233-7400
-----gislist-bounces@lists.geocomm.com wrote: -----
To: CWeaver@icfconsulting.com, gislist@lists.thinkburst.com
From: "Robert Heitzman" <rheitzman@hotmail.com>
Sent by: gislist-bounces@lists.geocomm.com
Date: 10/25/2003 12:24PM
Subject: Re: [gislist] Census Boundary Files Origin
Note that theCensus Designiated Places boundaries do not follow
administrative boundaries except where the Census Blocks were defined t=
o
follow admin boundaries. Whiile it is policy that blocks follow admin
boundaries it is not a legal requirement. Census needs would trump accu=
rate
administrative area definition. Ditto for the other area layers provide=
d
via
TIGER and COB.
My guess is that the procedure use to define Census Designiated Places =
was
to accept input from local representatives (County level most likely) a=
s to
which Census Blocks should be associated with a "place".
The LSAD_TRANS attribute value 'city' will most closely represent admin=
boundaries. 'CDP' records represent unincorporated "places" and they do=
not
represent an administrative division of land.
Another guess is that the Populated Places layer was developed more for=
map
annotation and as a general navigation referenece, not as a layer to
describe admin boundaries.
>1990 Census Boundary file (or 2000, it doesn't matter) of say a popula=
ted
>place. Does that reflect the boundary present in 1990, or was it actu=
ally
>created in/represents 1989 (etc) but was released in 1990
>
>
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