The
parish of Gjerpen was established as a municipality on 1 January 1838 (see
formannskapsdistrikt law). According to the 1835 census the municipality had a population of 4,381. Gjerpen was located east of the
town of Skien. It encompassed districts such as
Borgestad,
Bøle,
Gulset, and
Luksefjell. On 1 January 1856, an area of Gjerpen Municipality (population: 1,286) was
annexed by the growing town of Skien. On 1 January 1903, an unpopulated area of
Saude Municipality was transferred to Gjerpen. Again, on 1 July 1916, another area of Gjerpen Municipality (population: 1,332) was
annexed by the growing town of Skien. Then on 1 July 1920, an area of southern Gjerpen (population: 437) was transferred to the
town of Porsgrunn.
Name The municipality (originally the
parish) is named after the old
Gjerpen farm (; a corruption of ) since the first
Gjerpen Church was built there. The meaning of the first element is unknown. It is possibly the old name of a local river. The river name may have been derived from the word which means "the chattering one" or "the chuckling one", likely referring to the noise of the river. The last element is which means "
meadow" or "
pasture". ==Government==