Urban agriculture is touted as a strategy for more locally reliant food systems, yet there is little understanding of its potential food provisioning capacity. Using Detroit, Michigan as an example, we use secondary data to develop a methodology for estimating the acreage required to supply, as far as seasonally possible, the quantity of fresh fruits and vegetables consumed by city residents. We compare these requirements with a catalog of the publicly owned, vacant parcels in Detroit to assess the feasibility of producing significant quantities of the fresh produce consumed within city limits. We demonstrate that if high-yield, biointensive growing methods are used, 31% and 17% of the seasonally available vegetables and fruits, respectively, currently consumed by 900,000 people could be