Prohibition

I've long wondered, if alcohol consumption is so widespread, how the 18th Amendment ever passed -- 2/3 of Congress and 3/4 of states. On reading https://en.wikipedia.org/wiki/Volstead_Act it seems one aspect might be people expecting that liquor would be banned, gin and whisky and such, rather than all drinks; the Volstead Act limiting alcohol content to 0.5% was reportedly a big surprise.

OTOH Congress still had to write and pass that law, by a big enough margin to override a presidential veto, so there's still some mystery. Were 2/3 of Congress teetotalers?