One thing that I have wondered about though is did the square nail production in the States also run parallel with ahead of or behind say Britain or Europe.
The Audels "Carpenters and Builders Guide" (1923), states that at the end of the 18th century, American nail making machines were introduced to England where they were received w/ "great enthusiasm." (I assume the text is referring to cut nails).
And as far as Massachusetts goes, the text grants the first wire nail in America instead to a New Yorker in 1851.
It also states a German immigrant, a Catholic priest, who settled in Kentucky in 1876 formed the American Wire and Screw Nail Co. The priest learned the art of wire nails in his native Germany, so it sounds like some cross-continent stuff certainly went on.
The text does say Tauton, Massachusetts pretty much cornered the industry of "tack" making years ago.
Don't know how this info compares w/ what you've uncovered... anyway, looking forward to some more information from a scholar like Ken's contact.