Historic districts are a significant concentration, linkage, or continuity of sites, buildings, structures or objects united historically or aesthetically by plan or physical development. These resources may represent a local urban historic district within a city containing buildings related to a similar theme (such as commerce, manufacturing, college campus, etc.), or they may represent a rural area containing a series of plantations all from the same era that provide a representative example of typical residences in an area. An Historic District may also contain a series of archaeological sites or other resource types which exhibit some significant connection. The polygon represents the boundary of the district itself, encompassing all of the various contributing elements. Contributing elements to the district should be included in the appropriate data layer for each element: historic building, historic structure, archaeological site, or ethnographic resource. If a contributing element to a district does not fit within these defined cultural resource type categories, they can be included in the Other Cultural Resource data layers, with the specification of what type of feature they represent recorded.