In the 1970 Chicago UTPP approximately 60% of the
work locations were geocoded to TAZs with 10%
assigned to ZIP code areas, 10% to city, 10% to
county with the remainder identified as not reported.
The Census provided the 'best' geography available.
We made a considerable effort to assign all the trips to
TAZs but these files are no longer available.
Regarding county-to-county flows it would be reasonable to
expect that the TAZ, ZIP and city destinations were assigned
to the appropriate county. One can only guess what was done
with the ca 10% not reported data.
On Thu, February 22, 2007 3:41 pm, Ed Christopher wrote:
Chuck--If I understand you I could almost conclude
that in the Chicago
numbers that have been in play over 3 decades that we took the "place of
work not reported" for our resident workers and counted them as internal
flows. But that could not have happened. First the same pattern
exists all the counties I checked. Cook to Cook, Dupage, Kane, Lake,
Will and McHenry. The 1970 BEA numbers are low. It could be that our
1970 UTPP numbers were tweaked and if they were originally in the
neighborhood of the BEA numbers I could see why. I need to check out
that path as well.
Chuck how do your 1970 numbers compare? Are they more in line with
BEAs? Does anyone else have their 1970 CTPP numbers how do they
To give you an idea of magnitude here is what I am looking at for 1970.
1,931,034----2,105,178 Cook to Cook
27,104---32624 Cook to Dupage
5,403---9,056 Cook to Kane
8,888---18,624 Cook to Lake
698---951 Cook to McHenry
3,853---4,299 Cook to Will
I also have 43,076 Cook to elsewhere but I didn't add up all the BEA
I also looked at DuPage to all the other counties and the same pattern
-------- Original Message --------
Subject: Re: [CTPP] New Website--Old Data
Date: Thu, 22 Feb 2007 08:33:57 -0800
From: "Chuck Purvis" <CPurvis(a)mtc.ca.gov>
To: "Ed Christopher" <edc(a)berwyned.com>,"ctpp-news maillist"
The 1970 Census data on the BEA website shows a separate row, at the
very end of each county's table, for "place of work not reported". So,
Cook County Illinois has 181,911 resident workers with place-of-work not
reported, in 1970. Part of the mystery is solved.
I believe all of the "standard" 1970 Census tabulations did NOTdo
place-of-work allocation (imputation), so we would always see the "not
reported" data for any county, place or tract.
The 1970 Urban Transportation Package (UTP) probably had some
allocation (imputation) procedure to allocate the "not reported"
area-of-work to whatever geographies were used after the 1970 Census.
This is a guess. I don't have extensive records of the 1970 process. [I
do have the "Urban Transportation Factbook" published by the American
Institute of Planners and the Motor Vehicles Manufacturers Assocation,
in 1974, but it appears to be based on standard census tabulations, not
the UTP....?] Perhaps the answers are hidden in the Census Bureau (maybe
Phil can find the info before he retires next Friday? Or perhaps the
answers are in the archives - - JJ McDonnell's papers, or Alan
Pisarski's office....Perhaps some information is in the TRB Special
Report #145 (the 1973 Albuquerque Census conference.)
Charles L. Purvis, AICP
Principal Transportation Planner/Analyst
Metropolitan Transportation Commission
101 Eighth Street
Oakland, CA 94607-4700
(510) 817-5755 (office) [new, 8/1/05]
(510) 817-7848 (fax) [new, 8/1/05]
Census WWW: http://www.bayareacensus.ca.gov/
>> Ed Christopher <edc(a)berwyned.com>
02/21/07 8:40 PM >>>
Our friends (who I do not know) at the Bureau of
Economic Analysis who
do the Regional Economic Accounts revamped their historic (1970, 1980,
1990 and 2000) Journey to Work (JTW) data base and put a nice search
engine to it. For years I have sent people to the BEA sight for JTW
flows but with the new search engine and the 2000 data it is so easy to
use. For 2000 they have added flows by major industry at the county
level and by minor industry at the state level. You really need to
check it out. http://www.bea.gov/bea/regional/reis/jtw/
But then there is the nagging issue. Why do my historic CTPP/UTPP
numbers and BEA not match. In 1970 and 1980 the two sources look to be
off in different directions, but for 1990 they match and for 2000 it
looks like a small rounding difference. Getting into the detail,
attached is a comparison of the BEA/CTPP-UTPP numbers for Cook county
IL, specifically the Cook to Cook flows. In 1980 BEA is about 2K higher
out of 2M, but in 1970 BEA is in the neighborhood of 200K low. I know
this keeps coming up, but why? Is the pattern the same around the
country, BEA is high in 1980 and low in 1970? At some point we may need
to reconcile all this and pick one series or the other. Since I have
been tracking the Chicago region numbers
) for quite some time this
has always been a nagging headache.
How do all the numbers compare in your counties? Does anyone remember
why the 70s and 80s might not match?
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