SPRING VALLEY, Minn. (AP) — Community-supported agriculture farms in the Midwest have been putting fresh boxes of produce on the doorsteps of their urban and suburban neighbors since the 1990s. The volume of farmers trying their hand at the cooperative-based business formula has mushroomed, and CSA-grown boxes are getting delivered in all types of neighborhoods today.

CSA farms — otherwise referred to as subscription farms — vary in organization and the products they deliver. All of them are sustained by members who subscribe and pay upfront for a share of what's produced in a growing season....