 According to the 1835 census the municipality had a population of 3,557.Solum is located west of the city Skien, and encompassed districts such as Nenset, Tollnes, Flakvarp, Skotfoss, and Klyve.On 1 July 1916 an area with 1,042 inhabitants was moved to Skien, and on 1 July 1920 an area with 1,614 inhabitants was moved to Porsgrunn.