Dietary patterns may be influenced by the availability and accessibility within stores of different types of foods. However, little is known about the amount of shelf space used for healthy and unhealthy foods in different types of stores. We conducted measurements of the length of shelf space used for fruits, vegetables, and snack foods items in 419 stores in 217 urban census tracts in southern Louisiana and in Los Angeles County. Although supermarkets offered far more shelf space of fruits and vegetables than did other types of stores, they also devoted more shelf space to unhealthy snacks (mean 205 m for all of these items combined) than to fruits and vegetables (mean 117 m, p < 0.001). After supermarkets, drug stores devoted the most shelf space to unhealthy items. The ratio of the total shelf space for fruits and vegetables to the total shelf space for these unhealthy snack items was the lowest (0.10 or below) and very similar in convenience stores, drug stores, and liquor stores, was in a middle range (0.18 to 0.30) in small food stores, and was highest in medium-sized food stores (0.40 to 0.61) and supermarkets (0.55 to 0.72). Simple measurements of shelf space can be used by researchers to characterize the healthfulness of the food environment and by policymakers to establish criteria for favorable policy treatment of stores.