Absolutely true. It's a common misconception that the drinking age in the US is 21; federal law mandates that states outlaw the sale of alcohol to those under 21, but states have varying laws regarding the consumption of alcohol by minors.
You're portraying this wrong. Only 19 do not restrict underage drinking at all. 15 ban it in all cases and the rest have certain exceptions for location and family members. The majority ban underage drinking in most cases, not allow it.