This article is from the rec.food.drink.beer FAQ, by John Lock with numerous contributions by others.
This is just folklore that results from the way alcoholic strength is
measured. The alcohol content of mainstream U.S. beers is measured as
a percent of weight (abw). Canadian beers (and most other countries)
measure percent alcohol by volume (abv). A typical Canadian beer of
5% (abv) will be about the same strength as a typical U.S. beer at 4%
(abw).
 
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