Mapping Circular Area Demographic Patterns

What are the demographic characteristics of a circular area with a 10-mile radius from a given location/address? How do those demographic characteristics compare to those of a 5-mile radius from the same location? Imagine analyzing an almost infinite number of locations with many circular areas, each having a custom defined radius. This section provides an overview of using data and tools to develop and analyze circular area demographic characteristics for anywhere in the U.S. See the related Web section. More technical, step-by-step, operations on developing and using these data with GIS tools are reviewed in a related section.

Demographic-economic characteristics of the population and housing in a circular area may be approximated by using demographic-economic data tabulated for small area geographies. Small area geographies include census blocks, block groups, census tracts, ZIP code areas, among others.

Census block demographics are sourced from Census 2000 and Census 2010. Examine how demographics of alternatively defined areas (sets of census blocks) have changed between 2000 and 2010. Block group and higher level area demographic-economic data are sourced from the annually updated American Community Survey 5-year (ACS 5-year) estimates. This section is focused on using census block geography and demographics.

Mapping a Circular Area Based on Census Blocks
The following view illustrates how characteristics of a 1-mile radius circular area (blue colored census blocks) and a 3-mile radius circular area (green colored census blocks) from designated location (red dot) may be displayed on a map. Use tools described in this section to create such maps for any location in the U.S. for any radius. This application is in the Cupertino/Sunnyvale; Santa Clara County, CA area.

— view developed using CV XE GIS software; click graphic for larger view.

Supplemental graphics (click links to view) showing:
tabular profile of selected block attributes
zoom-in to location/block
zoom-in with blocks labeled with total population
use of site analysis tool
— population & housing units summarized/aggregated for area
thematic pattern view
— population per household by block with 1-mile radius blocks cross-hatched

Application Design
The application design starts with a location of interest. The latitude-longitude tool can be used to determine the latitude-longitude for an address. This example uses the address “1 Infinite Loop, Cupertino, CA 95014”. Copy and paste this address in the address edit box (no quotes) and press enter. The latitude-longitude values are 37.331711, -122.03018. The objective is to develop a 1-mile and 3-mile circular area profiles and shapefile for this location for use in a GIS project. Using the GIS project, views such as those shown above can be developed.

Using geospatial analysis tools, analysts and stakeholders can learn more about the demographic characteristics of a custom defined location vicinity. The 1-mile and 3-mile radius areas used here are only for illustration. There could be more circular areas and with any radius value. One location is used here for illustration; there might be many and at locations across the country.

The Next Step — Develop the Census Block Dataset
The Census block dataset is developed in these steps.
• Start OSEDA CAPS tool
• Take all default (or no) values except for items noted here.
• Enter the latitude and longitude values 37.331711 and -122.03018, respectively.
• Enter the two radii (1 3) in the “Enter up to 5 radius values” text box provided.
• Select California in the Select One or More States” dropdown .
• Click the checkbox “Check to generate txt file with standard codes …”
• Click Generate Report

The 1-mile radius report shows characteristics of the circular area with a Census 2010 total population of 29,042; the 3-mile radius report has a Census 2010 total population of 212,315.

Use the report as generated and optionally download the census block file generated (shown at the bottom of the report page (page generated after clicking “Generate Report” button described above. Click the link shown below to download the required file.

Save the downloaded file as c:\cv_caps\caps10c4131.txt. Any drive/folder/name may be used. Using this drive/folder/name makes the file naming consistent with next steps. You will need to create the folder c:\cv_caps.

Follow the detailed instructions described in this section to develop the circular area map views. Create your own shapefiles for any location for any size study area. Build a GIS project where you can view/analyze these data in context of other data.

About the Author
— Warren Glimpse is former senior Census Bureau statistician responsible for innovative data access and use operations. He is also the former associate director of the U.S. Office of Federal Statistical Policy and Standards for data access and use. He has more than 20 years of experience in the private sector developing data resources and tools for integration and analysis of geographic, demographic, economic and business data.

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