Shawn.. If my memory is correct, the MPO provided the TAZ identifiers to the Census Bureau Geography Division as a census block to TAZ equivalency file. The TAZ was qualified by a CTPP code. Your assumption about the TAZ split from 1990 to 2000 is probably correct, and would have been done by the MPO. Ed Christopher may remember more. Bob LaMacchia Retired (Chief, Geography Division) From: ctpp-news-bounces(a)chrispy.net [mailto:ctpp-news-bounces@chrispy.net] On Behalf Of Shawn Urbach Sent: Tuesday, May 30, 2017 10:33 AM To: &#39;ctpp-news(a)chrispy.net&#39; &lt;ctpp-news(a)chrispy.net&gt; Subject: [CTPP] CTPP 2000 TAZ ID Numbers Hello, I'm curious about TAZ identifiers for certain counties in the CTPP 2000 data set. For example, in Clay County, Missouri (FIPS #047), TAZs are numbered 299-376 with some delineated like 363A and 363B, while others aren't (with no letter concatenated). I'm assuming in this case, 363A and 363B were subdivided from 363. Is that correct? Thanks. Shawn Urbach Transportation Modeler | Mid-America Regional Council 600 Broadway Blvd., Ste. 200, Kansas City, MO 64105 816.701.8316 | <http://www.marc.org/> www.marc.org