the newly-designated kjøpstad (town) of Notodden (population: 4,821) was separated from Heddal to form a separate self-governing town as an enclave within Heddal Municipality. This left Heddal with 2,890 residents.

During the 1960s, there were many municipal mergers across Norway due to the work of the Schei Committee. On 1 January 1964, Heddal Municipality was dissolved and the