The present municipality was created during the local government reform in the late sixties and early seventies. Already in 1967 the City of Öregrund joined the City of Östhammar in a common municipality. It was the first time a former city joined another local government unit. By 1971 the new combined city became a municipality of unitary type and in 1974 more units were added.
In June 2018 the municipal council voted in favour of the building of Forsmark nuclear waste repository, with the final decision needing to be made by the Swedish government.[3]
Localities
All towns with over 200 inhabitants in 2000, from Statistics Sweden.
This is a demographic table based on Östhammar Municipality's electoral districts in the 2022 Swedish general election sourced from SVT's election platform, in turn taken from SCB official statistics.[4]
In total there were 17,497 Swedish citizens of voting age resident in the municipality.[4] 42.1% voted for the left coalition and 56.9% for the right coalition. Indicators are in percentage points except population totals and income.