North Humberside is a former postal county of England. It was introduced by the Royal Mail on 1 July 1974, when some addresses were altered in response to the changes in administration brought about under the Local Government Act 1972. The postal county corresponded approximately to the part of the new non-metropolitan county of Humberside north of the River Humber. All of the post towns included in the North Humberside had formerly been part of the Yorkshire postal county.