A referendum on lowering the voting age from 20 to 18 was held in Denmark

Denmark

Denmark is a Scandinavian country in Northern Europe. The countries of Denmark and Greenland, as well as the Faroe Islands, constitute the Kingdom of Denmark . It is the southernmost of the Nordic countries, southwest of Sweden and south of Norway, and bordered to the south by Germany. Denmark...

 on 19 September 1978. It was held after the Danish government lowering the age of majority

Age of majority

The age of majority is the threshold of adulthood as it is conceptualized in law. It is the chronological moment when minors cease to legally be considered children and assume control over their persons, actions, and decisions, thereby terminating the legal control and legal responsibilities of...

 from 20 to 18 in 1976. The change was approved by 53.8% of voters with a turnout of 63.2%. The electoral age had previously been lowered from 21 to 20 in a 1971 referendum

Danish electoral age referendum, 1971

A referendum on lowering the voting age from 21 to 20 was held in Denmark on 21 September 1971. The change was approved by 56.5% of voters, with a turnout of 86.2%. A previous referendum had been unsuccessful in lowering the electoral age to 18 years, which was introduced after a 1978 referendum...

, after a 1969 referendum

Danish electoral age referendum, 1969

A referendum on lowering the voting age from 21 to 18 was held in Denmark on 24 June 1969. The proposed change was rejected by 78.6% of voters with a turnout of 63.6%. Two years later, the electoral age was instead lowered to 20 years, and finally, after a 1978 referendum, to 18 years.-Results:...

had rejected lowering the electoral age to 18.

Results

Choice	Votes	%
For	1,224,455	53.8
Against	1,049,837	46.2
Invalid/blank votes	8,984	–
Total	2,283,276	100
Source: Nohlen & Stöver