Week 7 Lab: Census & Evalidator Queries

In today's lab, need to first answer two simple questions: 1) which Georiga 115th Congressional district has the most private timberland acreage and 2) how does the median real estate tax paid in this district compare to the other districts adjacent to it?  
In addition, answer the following:
  -  The problem you attempted to solve through your analysis (or map)
  -  The results of your analysis or what story you are trying to tell with your map
  -  Give me an example of how the analysis you just performed can be applied to an unrelated management problem or how a manager might use your map to address realistic management issues.

I will be out next Friday, so if necessary, this will be a two-week lab.

Query/Join/Select >> Answer!!!

This lab is about finding data about a region or regions of interest and answering both spatial and non-spatial questions based on that information.  While you focus on real estate taxes and the area of timberland within congressional districts today, you could be easily be dealing with timber volume and population within TMS regions, or population per square mile by male/female and or income or education levels within each state, …

To answer the questions posed at the beginning of this document, you will:

  1. query the FIA database for the most recent estimate of private timberland acreage by congressional district for Georgia.
  2. query US Census database (American Fact Finder) to determine the median real estate tax paid for each Georgia congressional district
  3. prepare both query results for joining in ArcGIS and join them to the US 115th congressional district shapefile (https://www.census.gov/geo/maps-data/data/cbf/cbf_cds.html)


  • create your lab workspace on the C:\ drive
  • download/copy the FIA Access database over to this workspace
  • start ArcMap; save the blank project to this workspace on the C:\ drive
  • create a new file geodatabase in this workspace in which you will store all of your data
  • download the 115th congressional district shapefile and import it into your file geodatabase


The FIA maintains records related to timberland for the entire US.  Users can submit queries against the most recent FIA database through the EVALIDator web application (http://apps.fs.fed.us/Evalidator/evalidator.jsp).  However, the FIA database web access tools are down for maintenance until 10/16/2017.  For this lab, I want you to use the Access Evalidator query form we looked at Monday to submit query for the most recent estimate of timberland acreage by congressional district by ownership.


Real Estate Taxes:

  • Use the American FactFinder query interface to retrieve table B25103, Mortgage Status by Median Real Estate Taxes Paid, reported by 115th Congressional Districts
  • Prepare the table in Excel
    • Fix the field headders; the estimate we’re interested in is HD01_VD01
    • Change any record whose value is NOT numeric to 10000
  • Import your table into your lab FGDB
  • Ensure you have 437 records


Determine Your Common ID Fields

  • There should be a 1-to-1 link between the geographic boundary files and the Census query result based on GEO.id and AFFGEOID
  • You need to do a little work on the FIA query result to create a common ID.  Georgia state FIPS is 13.  You can use a combination of STATEFP (state FIPS), CD115FP (congressional district FIPS) fields in the GIS boundary file to create a common ID between it and the FIA query results.
  • You can create these either before or after importing into ArcMap.

Join Tax Info to Boundaries

  • Load the boundary polygons
  • Load the tax information table
  • Load the FIA information table
  • Unselect all selected records
  • Join FIA Query to Boundaries based on the common field you prepared earlier

Determine the district with the largest amount of timberland

  • Select the Georgia congressional district with the largest amount of private timberland
  • Create a selection layer: Right-click on district boundary layer >> Selection >> Create Layer from Selected Features …
  • Use a Select By Location to select the surrounding polygon boundaries
  • Open the congressional district attribute and evaluate the selected records