Farmers' market interventions are a popular strategy for addressing chronic disease disparities in low-income neighbourhoods. With limited resources, strategic targeting of interventions is critical. The present study used spatial analysis to identify where market interventions have the greatest impact on healthy food access within a geographic region. All farmers' markets in a mixed urban/rural county were mapped and those that accepted Supplemental Nutrition Assistance Program (SNAP) electronic benefit transfer (EBT) cards identified. Households were grouped into small neighbourhoods and mapped. The area of 'reasonable access' around each market (walking distance (0·8 km; 0·5mile) in urban areas, driving distance (15 min) in rural areas) was calculated using spatial analysis. The percentage of county low-income households within a market's access area, and the percentage of county SNAP-participating households within an EBT-accepting market's access area, were calculated. The ten neighbourhoods with the most low-income households and with the most SNAP-participating households were then identified, their access areas calculated and mapped, and those lacking access identified. County-level gains resulting from improving market accessibility in these areas were calculated. None. Honolulu County, Hawaii, USA. Only 44 % of SNAP-participating households had EBT-market access. Six of the ten highest SNAP-participant neighbourhoods lacked access. Improving access for these neighbourhoods increased county-level access by 23 %. Market access for low-income households was 74 %. Adding markets to these low-income neighbourhoods without market access increased county-level access by 4 %. Geographic identification of market access demographics, and strategic targeting of EBT interventions, could improve regional access to healthy foods.