earliest abbreviation of "United States" as "U.S."?

[Christopher Philippo]

The phrase “United States of America” appears to have first been used as early as January 2, 1776 in a letter from Stephen Moylan to Col. Joseph Reed: “full and ample powers from the United States of America”
DeLear, Byron. “Who coined ‘United States of America’? Mystery might have an intriguing answer.” Christian Science Monitor. July 4, 2013. http://www.csmonitor.com/USA/Politics/2013/0704/Who-coined-United-States-of-America-Mystery-might-have-intriguing-answer

Not addressed in the above article was the relatively more trivial question of the first abbreviation of “United States” as “U.S.” The earliest that I can find at the moment is June 7, 1776, which early date might make it hard to beat (but certainly not impossible):

"Endorsed by Charles Thomson: '[J]une 7, 1776. No. 4. Resolutions moved June 7th. 1776. referred for consideration till to morrow respecting Independanc[e ory] of the U.S.’”
Resolution of Independence Moved by R.H. Lee for the Virginia Delegation, 7 June 1776.
http://founders.archives.gov/documents/Jefferson/01-01-02-0159

"Is it not an happy Circumstance that We have no other Engineer than Lieut. Colo. Carmovan? A Man of his Importance must not degrade himself by taking care of the intrenching Tools for common use: Some other Mode should be adopted for their preservation—I would have every Tool, on the Iron part stamped, & on the wooden branded, with the Letters U.S.—That they may be seized wherever found: Of which public Notice must be given.”
>From George Washington to Major General Thomas Mifflin, 13 March 1777.
http://founders.archives.gov/documents/Washington/03-08-02-0601

George Washington, John Adams, Thomas Jefferson, James Madison, James Monroe, Alexander Hamilton and many others were all using “U.S.” in correspondence and in at least the drafts of formal documents.  Jedediah Morse’s 1793 American Universal Geography uses “U.S. of America”; James Hardie’s 1799 An Account of the Malignant Fever, Lately Prevalent in the City of New-York has “U.S. Frigate”; one finds it in not just American but also London newspapers, etc.

Christopher K. Philippo

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