title_body: In the United States, is a beer required to state ABV on the bottle/label?
upvoted_answer: No, federal malt beverage labeling laws make it optional (though they do describe standards the label must meet if brewers do choose to add the alcohol content label.)  
  
  State laws, however, may require a brewer to add alcohol content to the label.  Clearly Delaware law (where Dogfish Head is based) must not.  
  
  In my experience, this is not terribly uncommon.  It is true that most beers do have alcohol content disclosed on the label, but I've run across quite a number that do not. 
  
  If you're interested in learning more about it straight from the source, it's available in the Electronic Code of Federal Regulations in Title 27, Chapter I, Subchapter A, Part 7—LABELING AND ADVERTISING OF MALT BEVERAGES.