It was 18 for a while during the 70’s. But kids were getting drunk and crashing and dying like crazy, so Ronald Reagan raised the drinking age back to 22 in the 1980’s with the threat of cutting highway funding to states that did not comply.
When I was on my first business trip at 18, I couldn't check into a hotel in Michigan by myself. I had to call me contact at (then) DaimlerChrysler to meet me for check in. I had a credit card that could buy a brand new car, but I couldn't get the key to a $75 hotel room due to age.
I later found out that, at the time, there was no law preventing me from acquiring the room, but the hotel policy was to not allow unaccompanied individuals under 21.
And insurance companies had enough sense to charge an arm and a leg to a single 24 year old with a Mustang. My insurance cost more than my car note back then.
