The large municipality of Lenvik was established on 1 January 1838 (see formannskapsdistrikt). In 1848, most of the mainland parts of Lenvik (population: 2,616) was separated to form the new Målselv Municipality, leaving Lenvik with 3,029 residents. Then in 1855, the northern part of Lenvik (population: 811) was separated to form the new municipality of Hillesøy. This left Lenvik with 2,757 inhabitants. On 1 January 1871, a small part of Lenvik (population: 70) was transferred to the neighboring municipality of Malangen.