Using Census Data to Define US Commuter “Megaregions”

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Geographers from Dartmouth College and the University of Sheffield have used visual interpretation combined with statistical analysis to achieve a better understanding of the economic links that connect the millions of commuters within the United States.  The complex networks of daily traveling of workers outline a structure in which economic systems, natural resources, and infrastructure play heavy roles.  The paper offers a unique insight into how “economic flows and megaregional boundaries are related.”  The researchers looked across the entire country and used the Census Tract data from the Census Bureau’s American Community Survey (ACS) between the years of 2006 and 2010.  The Census Tract uses an average population of 4,000 as its spatial unit.  This unit was geographically big enough for researchers to represent a significant number of commuting workers.

Two methods were used to work through the data.  The first was a visual heuristic approach that filtered the ACS data based on distance and flow volume to better measure “long distance commutes.”  The issue was that the result required “subjective guesswork” to determine regional edges because the output did not produce any.  The second method was an algorithmic approach that helped to bypass that “subjective guesswork” which flawed the first approach.  This was achieved by finding spatially contiguous areas that an individual would not ordinarily be able to determine visually.

Commutes of fifty miles or less in the Bay Area.

Commutes of fifty miles or less in the Bay Area. Source: Nelson and Rae 2016.

The study was able to conceptualize the complexity of accurately capturing the spatial economic trends within such a national social element.  Within the article’s website one can visualize the difference, and inherent complexity, in the final visual outputs between the two methods the researchers pursued.  What the geographers wanted to emphasize is that spatial data visualizations are indeed subjective, and should be understood as so.  They also wanted to show the fact that economic geography is another one of the myriad of ways we can better define community and continue to better “assess the needs of our society.”

Map of defined commuter megaregions.

Map of defined commuter megaregions. Image: Nelson and Rae, 2016.

More:

Nelson, G. D., & Rae, A. (2016). An Economic Geography of the United States: From Commutes to Megaregions. PloS one11(11), e0166083. DOI: 10.1371/journal.pone.0166083

Garrett, Dash, Nelson, et al. “Geographers Provide New Insight into Commuter Megaregions of the US.” Phys.org – News and Articles on Science and Technology. N.p., 30 Nov. 2016. Web. 10 Dec. 2016. <http://phys.org/news/2016-11-geographers-insight-commuter-megaregions.html>.

Article by Brayden Donnelly

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