Tuesday, July 5, 2016

Parcel Data, Who Needs it

Just about everyone.  At a recent parcel gathering there was some discussion about re-discovering which federal agencies need parcel data. 

As our computing and analysis capability expands so does our need for more granular and more detailed information. An overview of the granularity of geographic units in the US shows the increasing density and decreasing size of the unit of land about which we can compile information.

50 states
3,200 counties or equivalents
40,000 functional governmental units
57,000 7 ½ minute quadrangles to cover continental US and Hawaii
66,000 Census tracts
3.8 million square miles in the US
11 million Census blocks
133 million residential housing units in the US
(5.6 million commercial buildings)
150 million parcels
324 million people in the US

Parcels are the logical division of land for compiling information about use, value, and ownership. And who and what agencies need to know about use, value, and ownership?  Almost every agency at some level needs this data.

In 2008 the Cadastral Subcommittee interviewed 30 federal agencies to ascertain their use of or need for locally produced parcel data and for the responding agencies 16 had a clear identified need.  (http://nationalcad.org/download/Federal_Agencies_-_final.pdf)
Since 2008 as agencies have become more familiar with the availability of more detailed information and the ability to use and analyze bigger data sets (think GIS big data) has arrived, the identified needs and uses for parcel data have grown.

And what information about parcels is needed?  Other than guarded concerns about personally identifiable information (PII) the basic information needs are as originally defined nearly a decade ago (http://nationalcad.org/download/CadNSDI-Version2-Documentation.zip) and include use, value, and ownership.  Several agencies have expanded data needs, typically in more defined areas, such as urban areas, commercial parks, wildland fire interface areas, or farm program participation parcels.  Some of the extended attributes in more focused areas include, rental or owner occupied, mortgage status, tax bill payment status, farm field activity, new building activity, structure condition, and commercial lease values. 

Defining which attributes to aggregate and what standard field names and attribute types to use are not barriers to building a national parcel dial tone.  These things have all been studied and are known well enough to start.  There will be updates of course.  How many times a year does your mobile phone provider update your operating system or connection parameters? 

Who needs parcels?  There are enough needs and uses that they should just be there.

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