Newmarket was a rural district in Cambridgeshire, England from 1894 to 1974. It surrounded the town of Newmarket, in Suffolk, on the north, west and south sides.
The district was created in 1894 as the Cambridgeshire part of the Newmarket rural sanitary district (the Suffolk part becoming Moulton Rural District)
It was abolished in 1974 by the Local Government Act 1972 and went on to form part of the East Cambridgeshire district.
References
Newmarket Rural District Wikipedia(Text) CC BY-SA