Va. Code § 15.2-4305
On or before November 1 of each year or any other annual date selected by the locality, any owner or owners of land may submit an application to the locality for the creation of a district or addition of land to an existing district within the locality. Each district shall have a core of no less than 200 acres in one parcel or in contiguous parcels. A parcel not part of the core may be included in a district (i) if the nearest boundary of the parcel is within one mile of the boundary of the core, (ii) if it is contiguous to a parcel in the district the nearest boundary of which is within one mile of the boundary of the core, or (iii) if the local governing body finds, in consultation with the advisory committee or planning commission, that the parcel not part of the core or within one mile of the boundary of the core contains agriculturally and forestally significant land. No land shall be included in any district without the signature on the application, or the written approval of all owners thereof. A district may be located in more than one locality, provided that (i) separate application is made to each locality involved, (ii) each local governing body approves the district, and (iii) the district meets the size requirements of this section. In the event that one of the local governing bodies disapproves the creation of a district within its boundaries, the creation of the district within the adjacent localities' boundaries shall not be affected, provided that the district otherwise meets the requirements set out in this chapter. In no event shall the act of creating a single district located in two localities pursuant to this subsection be construed to create two districts.
Va. Code § 15.2-4305