“We must build a kind of United States of Europe.”

Report on Manufactures (1791)
Context: If the system of perfect liberty to industry and commerce were the prevailing system of nations, the arguments which dissuade a country in the predicament of the United States, from the zealous pursuits of manufactures would doubtless have great force. (...) But the system which has been mentioned, is far from characterising the general policy of Nations. The prevalent one has been regulated by an opposite spirit. The consequence of it is, that the United States are to a certain extent in the situation of a country precluded from foreign Commerce. They can indeed, without difficulty obtain from abroad the manufactured supplies, of which they are in want; but they experience numerous and very injurious impediments to the emission and vent of their own commodities. (...) In such a position of things, the United States cannot exchange with Europe on equal terms, and the want of reciprocity would render them the victim of a system, which should induce them to confine their views to Agriculture and refrain from Manufactures. A constant and increasing necessity, on their part, for the commodities of Europe, and only a partial and occasional demand for their own, in return, could not but expose them to a state of impoverishment, compared with the opulence to which their political and natural advantages authorise them to aspire.

After UK Foreign Secretary Douglas Hurd claimed lifting the arms embargo to Bosnians would create a "level killing field", as reported in 'Thatcher says massacre brings shame on west' by Philip Webster and Robert Morgan in The Times (14 April 1993)
Post-Prime Ministerial

Collected Works, Vol. 21, p 341.
Collected Works

Message to the Senate (19 August 1914)
1910s

Océan - Tas de pierres (1942)

Attributed to Washington in "Farewell to the United States of Europe: long live the EU!" by André Fontaine at Open Democracy (29 November 2001) http://www.opendemocracy.net/democracy-europefuture/article_344.jsp. It appears to have originally circulated in French:
:: Je suis citoyen de la Grande République de l'Humanité. Je vois le genre humain uni comme une grande famille par des liens fraternels. Nous avons jeté une semence de liberté et d'union qui germera peu à peu dans toute la Terre. Un jour, sur le modèle des Etats-Unis d'Amérique, se constitueront les États-Unis d'Europe. Les États-Unis seront le législateur de toutes les nationalités.
: An anonymous blogger in "Did George Washington predict a "United States of Europe"? (30 January 2010) http://racehist.blogspot.com/2010/01/did-george-washington-predict-united.html showed that it derived from Gustave Rodrigues, Le peuple de l'action: essai sur l'idéalisme américain (A. Colin, 1917), p. 207:
:: Washington écrivait à La Fayette qu'il se condérait comme « citoyen de la grande république de l'humanité » et ajoutait : « Je vois le genre humain uni comme une grande famille par des liens fraternels ». Ailleurs il écrivait, prophétiquement: « Nous avons jeté une semence de liberté et d'union qui germera peu à peu dans toute la terre. Un jour, sur le modèle des Etats-Unis d'Amérique, se constitueront les États-Unis d'Europe. »
: A translation by Louise Seymour Houghton ( The People of Action: An Essay on American Idealism (1918) http://books.google.com/books?id=b8Y9AAAAYAAJ) reads:
:: Washington wrote to Lafayette that he considered himself a "citizen of the great republic of humanity," adding: "I see the human race a great family, united by fraternal bonds." Elsewhere he wrote prophetically: "We have sown a seed of liberty and union that will gradually germinate throughout the earth. Some day, on the model of the United States of America, will be constituted the United States of Europe." [pp. 209-210]
: The first two quotations come from a letter to the Marquis de Lafayette of 15 August 1786 (see above) as quoted in Joseph Fabre's Washington, libérateur de l'Amérique: suivi de Washington et la revolution Américaine (Ch. Delagrave, 1886), and the third is also found in that source where, although placed between quotation marks, it is clearly intended as the author's own comments on what "Washington and his friends" were saying to the world by establishing the American Constitution. Gustave Rodrigues mistakenly printed Fabre's words as Washington's alongside some actual observations of his from a letter to Lafayette, and so created the misquotation.
Misattributed

Vancouver Province, April 6, 2004: On Taxes.
2004

As quoted in Marvin Zonis (1991), Majestic Failure: The Fall of the Shah, page 65
Attributed