How to identify food deserts: measuring physical and economic access to supermarkets in King County, Washington.
OBJECTIVE
We explored new ways to identify food deserts.


METHODS
We estimated physical and economic access to supermarkets for 5 low-income groups in Seattle-King County, Washington. We used geographic information system data to measure physical access: service areas around each supermarket were delineated by ability to walk, bicycle, ride transit, or drive within 10 minutes. We assessed economic access by stratifying supermarkets into low, medium, and high cost. Combining income and access criteria generated multiple ways to estimate food deserts.


RESULTS
The 5 low-income group definitions yielded total vulnerable populations ranging from 4% to 33% of the county's population. Almost all of the vulnerable populations lived within a 10-minute drive or bus ride of a low- or medium-cost supermarket. Yet at most 34% of the vulnerable populations could walk to any supermarket, and as few as 3% could walk to a low-cost supermarket.


CONCLUSIONS
The criteria used to define low-income status and access to supermarkets greatly affect estimates of populations living in food deserts. Measures of access to food must include travel duration and mode and supermarket food costs.
Department of Urban Planning, College of Architecture and Urban Planning, Ball State University, Muncie, IN 47306, USA. jjiao@bsu.edu
Junfeng
J
Jiao
Anne V
AV
Moudon
Jared
J
Ulmer
Philip M
PM
Hurvitz
Adam
A
Drewnowski
D004779:Environment Design; D019649:Food Industry; D005523:Food Supply / Q000191:economics* / Q000706:statistics & numerical data; D040362:Geographic Information Systems; D011204:Poverty Areas; D012111:Residence Characteristics; D014861:Washington