The name 'Dacorum' comes from the "Hundred of Dacorum" one of the ancient administrative units of Hertfordshire. It is probably a latinised version of the Anglo Saxon word for Danish. In October 1984 the Council was granted borough status and became Dacorum Borough Council.
Dacorum covers 81 square miles of West Hertfordshire where it borders with Bedfordshire and Buckinghamshire. It extends Northwest almost from Watford, along the valleys of the Gade and Bulbourne rivers to the picturesque Chiltern Hills. Dacorum consists of four main towns - Hemel Hempstead, Berkhamsted, Tring and Kings Langley together with many outlying rural villages such as Aldbury, Wigginton and Flamstead. The total population is around 155,000 which is 13% of the total population of Hertfordshire. The main lines of communication through the Borough are the A41 bypass, the A4251, the Euston to Glasgow (West Coast main line) railway and the Grand Union Canal. The M1 runs down the eastern boundary and the M25 crosses the south-eastern tip of the Borough.