7 C.F.R. § 25.503 – Rural areas.

(a) What constitutes “rural”. A rural area may consist of any area that lies outside the boundaries of a Metropolitan Area, as designated by the Office of Management and Budget, or, is an area that has a population density less than or equal to 1,000 persons per square mile, the land use of which is primarily agricultural.
(b) Exceptions to the definition. On a case by case basis, the Secretary may grant requests for waiver from the definition of “rural” stated in paragraph (a) of this section upon a showing of good cause. Applicants seeking to apply for a rural designation who do not satisfy the definition in paragraph (a) of this section must submit a request for waiver in writing to the Deputy Administrator, USDA Office of Community Development, Reporters Building, Room 701, STOP 3203, 300 7th Street, SW., Washington, DC 20024-3202. Requests must include:
1. (1) The name, address and daytime phone number of the contact person for the applicant seeking the waiver; and
2. (2) Sufficient information regarding the area that would support the infrequent exception from the definition.
(c) Waiver process. The Secretary, in consultation with the Department of Commerce, will have discretion to permit rural applications for communities that do not meet the above rural criteria.