Dacorum Council was created in 1974 following a review of local government in England and Wales.
Five smaller council areas, those of the borough of Hemel Hempstead, the urban districts of Berkhamsted and Tring, and the rural districts of Hemel Hempstead and Berkhamsted were merged.
The new administrative area also took in small parts of the rural districts of Watford and St Albans. The bringing together of seven areas is marked by the seven oak leaves which surround the Tudor rose in the centre of the borough's logo.
By decree of Queen Victoria, Hemel Hempstead had been granted the distinction of being a borough. Given that Berkhamsted and Tring also have historical significance, the newly formed district council petitioned Parliament that Dacorum be granted 'borough' status. The appeal was successful and on 1 April 1984, Dacorum became a borough. As a borough it was entitled to elect a mayor and to adopt armorial bearings – which most people refer to as a coat of arms.
The new area needed a name that did not imply that any one of the seven areas had dominance over the others.
The opportunity was taken to revive a name which had been in use since mediaeval times but had fallen out of common use 200 years before. "Dacorum" was one of the country’s ancient land divisions – a "hundred".
Although scholars are not in total agreement on the origins of the word, the popular interpretation is that it's a mediaeval Latin translation of the Anglo-Saxon word for Dane or Danish. Danish settlers were common in the coastal districts of East Anglia but few ventured this far west, so their residence here may have caused the location to be referred to as a place "where some Danes live". However, no evidence of a Danish settlement was found.