The schema.org areaServed property can be used to call out the geographic area where a service or offered item is provided.
The types containing the areaServed property are ContactPoint, DeliveryChargeSpecification, Demand, Service, Offer, and Organization. Keep in mind that any subtypes of these aforementioned types have access to the same properties as their parent, so areaServed can also be used by types such as LocalBusiness, MedicalClinic, and FincancialService, all of which are subtypes of Organization.
From within any one of these types, the areaServed property can connect to the AdministrativeArea, GeoShape, or Place types. This property will also accept text, but we generally recommend linking to a Wikipedia or Wikidata page that represents the area (or areas) served.