In this study, we examined urban agricultural production potential in New York city (NYC) in the United States and Osaka in Japan in a comparative study not only due to their similarities in population and region size but also differences in historical geographies and urban formation processes. We utilized available high-resolution land-use-and land-cover data to map and empirically compare size, land use, and spatial patterns of sites of current urban agriculture as well as land areas with potential for expanding urban agriculture. By linking current vegetable production data, and potential future urban agriculture land with per capita vegetable consumption data, we were able to estimate the total potential population that could be supported by locally produced vegetables. Our results showed that by scaling up current vegetable production in existing NYC community gardens, potential agricultural productivity on other underutilized or vacant land was 0.26 kg/m(2)/year for NYC. For Osaka, existing rice and dry fields could produce in comparison 0.54 and 0.74 kg/m(2)/year, respectively. By combining potential urban and peri-urban vegetable production measures with estimated needed vegetable caloric intake per person per year, we show that the current vegetable production levels in Osaka can feed approximately 0.50 million people. However, if the region maximizes existing underused speculative dry fields, urban and peri-urban agriculture could feed approximately 3.4 million people per year. In NYC, current vegetable production in community gardens is estimated to feed only 1700 people per year. However, if NYC maximized all available urban vacant lots and other open spaces, potential vegetable production could provide food annually for 0.55 million people. We discuss how though both community gardens in NYC and remaining rice and dry fields in Osaka have been out of formal city planning with clear land-use definition in zoning, these agricultural practices have nonetheless emerged as important sources of local food production and nutrition on the one hand, and sites of social benefit on the other.