Municipalities can be further divided into boroughs or stadsdelsnämnder. The existence of such divisions are at the discretion of the municipality itself which also can decide to hold local referendum on whether a borough or part of the municipality should secede and form a separate municipality. However the question of whether a new municipality will at all be created is at the discretion of the Swedish Government.
In the middle of the 20th century several municipal reforms were implemented, which successively and drastically reduced their numbers, to the current 289 municipalities. The last major reform in 1971 abolished the Cities of Sweden as separate administrative entities and made them centers of the new larger municipalities. The cities, most of them with centuries old and in some cases more than 1000 year old traditions, are in spite of this still percieved as cities even if they are no longer in the formal sense, cities as such. Also metropolitan areas, such as Stockholm, are formally municipalities.