The reason the voting age is 18 is because the draft age is 18. The argument is that if one is old enough to die for one’s country, one is old enough to vote.
I am in favor of raising the age for both to 21.
Subject is being changed, however raising the age to 21 will create a shortage and 18 year olds are able bodied (Draft is designed to protect your homeland, 18 is old enough to fight). States should determine their own drinking/smoking age.