Rural districts were based on the areas of existing rural sanitary districts, which had been created in 1875. Sanitary districts were themselves based on the poor law unions, and frequently contained areas in more than one county.
The 1894 Act provided that where a rural sanitary district was situated in more than one administrative county the part in each county would become a separate rural district. There were however exceptions "where for special reasons the county council otherwise direct" involving very small areas. In these cases there were three options:
Rural districts could be in more than one administrative county
Parishes could be united to a neighbouring rural district or districts in the same county
Parishes in one administrative county could be administered by a rural district in another
There were only a handful of cross-county rural districts, often due to complicated county boundaries unsuited to administration of local government services. These were: