The district's area was further enlarged in 1977, when some municipalities of neighbouring districts (Gandersheim and Osterode am Harz) joined the Northeim district.
Kreisi pindala laiendati veelgi 1977. aastal, kui mõned naaberkreiside vallad (Gandersheim ja Osterode am Harz) ühendati Northeimi kreisiga.