The Borough of Dacorum is a local government district in Hertfordshire, England that includes the towns of Hemel Hempstead, Berkhamsted, Tring and Kings Langley. The district, which was formed in 1974, had a population of 137,799 in 2001. Its name was taken from the old hundred of Dacorum which covered approximately the same area. It is the westernmost of Hertfordshire's districts, being bordered to the west by the Chiltern and Aylesbury Vale districts of Buckinghamshire.