Patty, I am not really sure if having PUMAs that cross large city boundaries cause any serious problems. Geographic continuity is a good practice. The only use that PUMA can give you is having access to household sample record as a whole in a large area. Affiliation to city for 5% sample record does not reveal anything about the city. As long as PUMAs are aggregation of Tracts, one can relate the sample records to other tables and estimate expanded household characteristics. It would be nice if aggregation of PUMAs would become cities (for large ones) but that is fairly hard to achieve in general.

Arash

Arash Mirzaei, P.E.
Senior Program Manager
Model Development and Data Management

North Central Texas Council of Governments (NCTCOG)
Tel: (817) 695-9261
Fax: (817) 640-3028
Email: amirzaei@nctcog.org

From: ctpp-news-bounces@chrispy.net [mailto:ctpp-news-bounces@chrispy.net] On Behalf Of Patty Becker
Sent: Wednesday, November 09, 2011 4:05 PM
To: ctpp-news@chrispy.net
Cc: dargak@michigan.gov
Subject: [CTPP] PUMAs

This is time critical. If you have a response for us, please reply immediately to pbecker@umich.edu and/or to the list.

We are having a big problem with PUMA delineation in Michigan because of the Census Bureau's rule that PUMAs must be contiguous.

They apparently had this rule in the past, which is why we didn't catch it as a "change" in the regulations. However, they didn't enforce it, so we were able to have non-contiguous PUMAs where we needed them. Now they don't want to let us do it. The biggest reason, I believe, is that this time they're using software into which they've programmed the rule that requires contiguity.

The City of Detroit has two enclave cities, plus six communities adjoining its eastern boundary. The rest of the county lies to the west of the city. These 8 communities used to be 1 PUMA, but they've shrunk below 100,000, and therefore would need territory added from elsewhere (in Wayne, their county, presumably).  The main point is: we need PUMAs which together delineate Detroit exactly. Under the contiguity rule, that's impossible.  We have another issue surrounding the City of Flint and Genesee,its county, where the other counties in the state planning/service area centered on Flint lie to either side of Genesee. Logically, these two counties would form one PUMA, while other PUMAs would be formed within the Genesee boundary. We used to have this arrangement.

We need to know if any similar issues have come up in other states. If so, what are you doing about it?  Please let us know immediately.

Thanks much,

Patty Becker

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