Our agency is attempting to get a jump on determining what potential changes may occur to our urbanized area based on the new census data and the proposed 2010 Census Urban Area criteria. I'm sure that we're not the only ones out there doing this. We are initially just looking at the most basic criteria involving the population density requirements, but we have already run into an issue that we need clarification on with regards to what should be used as the starting geographic "container".

Specifically, section 1, Identification of Initial Urban Area Cores, of the proposed criteria (Federal Register, Vol. 75, No. 163, August 24, 2010) is causing some confusion.  That section outlines a series of steps that must be followed in the process to define urban areas.  The first step calls for the identification of census tracts that have land area less than three square miles and a population density of at least 1,000 people per square mile.  Stated next in the criteria: “If a qualifying census tract does not exist, then one or more contiguous census blocks that have a population density of at least 1,000 people per square mile are identified and aggregated.”  Then it is stated, “This aggregation of continuous census tracts or census blocks, as appropriate, would be known as the initial urban area core.” 

Our question:  What is the starting geography within which we look for qualifying census tracts?   Within a county?  A metropolitan statistical area?  A combined statistical area?  Key to the second and third statements is the use of the words, “IF” and “OR.”  “IF” no qualifying tracts are found, then look for qualifying blocks.  The initial urban area core is an aggregation of continuous census tracts OR census blocks.  Since the initial core identified in step one is either tracts OR blocks, not both, we need to know the geographic container within which we look for qualifying tracts or blocks.

As a side question - is anyone aware of software/GIS scripts already available out there capable of running a 2010 urbanized area delineation analysis? I do realize that since the criteria have not yet been finalized it is very unlikely that any are available - at least from commercial vendors.

Any help would be appreciated, thanks,

Mike Conger

Michael D. Conger, P.E.
Senior Transportation Engineer
Knoxville Regional TPO
400 Main Street, Suite 403
Knoxville, TN 37902

Ph: 865-215-3813
Fax:865-215-2068