Last week the Census Bureau (CB) sent a letter to the State Data Centers(SDCs) asking them to participate in the delineation of the Public Use Microdata Sample (PUMS)zones. A copy of that letter and the criteria used in defining the zones (know as PUMAs) can be found on the TRB census data subcommittee's web page at http://www.mcs.com/~berwyned/census/ The direct link for the information is http://www.mcs.com/~berwyned/census/articles/pumaguidelines.pdf For those new to the PUMS game an article talking about the importance of PUMS data for transportation planning can be found in the last "status report" at http://www.mcs.com/~berwyned/census/newsltr/sr0401.html#pums Since PUMS data is becoming increasing more useful in the context of transportation planning it is important for MPOs (and state DOTs) to be close to the development of the PUMAs (pums zones) in their areas--especially for the larger MPOs and for state planning. Although the process of delineating the PUMAs is left to the SDCs, MPOs and state DOTs should contact their SDC and let them know that they have an interest in participating or assisting with the process. In 1990 I know there were several MPOs that actually defined the zones in their planning areas. The SDCs can be found at http://www.census.gov/pub/sdc/www/sdctxt.html If you contact your SDC and you find that they are NOT participating in the program please let us know by contacting Nandu Srinivasan at nanda.srinivasan(a)fhwa.dot.gov ed christopher chair, trb subcommittee on census data for transportation planning