The drinking age in Minnesota has changed several times in the last 40 years. According to the Minnesota Legislative Reference Library,
Prior to 1973, the drinking age was the age of legal adulthood (age of majority), which was 21... In 1973, the age of majority was lowered from 21 to 18. This dropped the drinking age to 18... The legal drinking age was raised to 19 in 1976... The drinking age was raised to the current age of 21 in 1986... It included a grandfather clause: persons who were 19 years old by September 1, 1986 were treated as 21 year olds for liquor law purposes.
And so, the legal drinking age in Minnesota is 21.