Mapping the Urban-Rural Continuum

Author

John Johnson

Published

September 29, 2020

Modified RUCA codes that distinguish between cities and suburbs

Rural-Urban Commuting Area Codes (RUCA) are created by the USDA to “classify U.S. census tracts using measures of population density, urbanization, and daily commuting.” The USDA also provides a zip code-based RUCA file. These are particularly useful for public opinion researchers who know an interview respondent’s zipcode but possibly little other geographic information.

The basic RUCA codes use a single code for urbanized areas–a broad Census Bureau designation which includes basically all the built-up parts of a Metropolitan Statistical Area. Public opinion researchers typically want to distinguish between “urban” and “suburban” communities, both of which are included in the Census definition of “urbanized areas” and thus also RUCA code #1.

To solve this problem, I create an additional code for “principal cities.” Using the Missouri Census Data Center’s Geographic Correspondence Engine, I created a population-weighted crosswalk between 2010 ZCTAs (zip codes) and 2014 places. I then identify the census-designated principal cities of metropolitan statistical areas (as of 2020). I exclude the principal cities of micropolitan statistical areas.

A zip code is classified as a “principal city zip” if a majority of the population resides in a principal city.

The resulting zipcode-to-modified-RUCA file is available to download at this link (right-click and choose “save link as”). The zipcode to principal cities crosswalk is available in the source-data folder of this repository.

The modified RUCA file also includes additional suggested summary classifications combining multiple existing codes.

Here is a table showing the codes along with the number of zipcodes and total national population.

ruca_new label_new ruca6 ruca5 zips population
0 Principal city Principal city Principal city 3,914 109,596,588
1 Suburban core Suburban core Suburban core 12,671 133,895,135
2 Metropolitan area high commuting: primary flow 30% or more to a UA Exurbs Exurbs 7,026 25,928,062
3 Metropolitan area low commuting: primary flow 10% to 30% to a UA Exurbs Exurbs 897 2,142,882
4 Micropolitan area core: primary flow within an Urban Cluster of 10,000 to 49,999 (large UC) Large towns (10-50k) Large towns (10-50k) 2,182 21,906,755
5 Micropolitan high commuting: primary flow 30% or more to a large UC Large towns (10-50k) Large towns (10-50k) 2,788 5,184,196
6 Micropolitan low commuting: primary flow 10% to 30% to a large UC Large towns (10-50k) Large towns (10-50k) 636 1,113,485
7 Small town core: primary flow within an Urban Cluster of 2,500 to 9,999 (small UC) Small towns (2.5-10k) Rural (less than 10k 2,039 11,226,057
8 Small town high commuting: primary flow 30% or more to a small UC Small towns (2.5-10k) Rural (less than 10k 1,378 1,933,200
9 Small town low commuting: primary flow 10% to 30% to a small UC Small towns (2.5-10k) Rural (less than 10k 538 816,103
10 Rural areas: primary flow to a tract outside a UA or UC Isolated rural Rural (less than 10k 6,899 9,124,824

Application examples

For example uses of these RUCA codes see: