when did sikkim become full fledged state of india
History of Sikkim Prime Minister Dorji appealed to the Indian Parliament for representation and change of status to statehood. On 14 April 1975, a referendum was held, in which Sikkim voted to merge with the union of India. Sikkim became the 22nd Indian State on 26 April 1975. On 16 May 1975, Sikkim officially became a state of the Indian Union and Lhendup Dorji became head of State (chief minister).