Lakhimpur is an administrative district in the state of Assam in India. The district headquarters are located at North Lakhimpur. The district is bounded on the north by Siang and Papumpare District of Arunachal Pradesh and on the east by Dhemaji District and Subansiri River. Majuli Sub Division of Jorhat District stands on the southern side and Gahpur sub division of Sonitpur District is on the West.

Lakhimpur figures largely in the annals of Assam as the region where successive invaders from the east first reached the Brahmaputra. The most prominent of them were the Sutiya rulers who held the areas of the present district for long, until the outbreak of the Ahom-Sutiya war in the 16th century and eventually the area came under the rule of the Ahom dynasty. The Burmese, who had ruined the native kingdoms, at the end of the 18th century, were in 1826 expelled by the British under the Treaty of Yandaboo. They placed the southern part of the state, together with Sivasagar under the rule of Raja Purandhar Singh; but it was not till 1838 that the whole was taken under direct British administration.

Lakhimpur district used to have several other districts of Arunachal Pradesh within its fold and was known as the Lakhimpur Frontier Tract. After independence, the district contained the present day Dibrugarh district, Tinsukia district and Dhemaji district. Its headquarters was at Dibrugarh.

In 1976, Dibrugarh district was separated from Lakhimpur. This was repeated on 14 October 1989, with the formation of Dhemaji district.

Economy of Lakhimpur is mainly based on agriculture. Major crops are rice, tea, mustard, sugarcane, etc. Small number of SSc and MSc industries [clarification needed] are located in the district.

The district is multi-cultural and multi-ethnic in nature. Assamese speakers of Sutiya, Ahom, Koch community along with Mishing tribe dominates the district. Other groups include Assamese and Bengali speaking Muslims which have a sizeable population in the district. Tea tribes community also called Adivasi forms nearly one-tenth of the district’s population and mainly resides in the western and northern part of the district along the foothills. Other communities include Bengali Hindus, Nepali speakers and Bodos.

According to the 2011 census Lakhimpur district has a population of 1,040,644,roughly equal to the nation of Cyprus or the US state of Rhode Island. This gives it a ranking of 435th in India (out of a total of 640). The district has a population density of 457 inhabitants per square kilometre (1,180/sq mi) . Its population growth rate over the decade 2001-2011 was 17.06%. Lakhimpur has a sex ratio of 965 females for every 1000 males, and a literacy rate of 78.39%