To the point of the actual question, of which company in the United States produced the first aluminum bicycles I'd have to say that I've never heard of a US company doing so prior to Luminum which after looking at the Bicycle Quarterly, is the bike I was thinking of.

There challenge was for $500 to other bicycle manufacturers.

Also, to another post that was erroneously made to this thread, Cannondale's dropouts are nothing like the Klein dropouts. In fact, I've never seen a dropout like the Klein dropout. Cannondale did use the cantilevered design for years, but this was because it was lighter and stiffer than traditional seat stays. Nothing whatsoever to do with Klein dropouts. I can't believe how much disinformation is out there concerning Klein and Cannondale.

Sheesh the next thing I'll read is that Joe Montgomery of Cannondale tried to invest millions of his own money to save the company, instead of committing securities fraud and fleecing Cannondale (when they were publicly traded as symbol BIKE) of millions in fraudulent loans.