“The League [of the Hodenosaunee] favorably impressed the White settlers, and some historians believe it to have been one of the models on which the Constitution of the new United States of America was based.”

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

At a town hall meeting in North Berwick. http://www.pressherald.com/2016/08/25/aclu-of-maine-asks-lepage-to-produce-binder-of-recent-maine-drug-arrests/ (August 25, 2016)

2009, A New Beginning (June 2009)

Preface
The Great Rehearsal (1948)

1830s, Illinois House Journal (1837)

An American Peace Policy (1925)

Gordon Humphrey

Source: The Secret Teachings of All Ages (1928), p. xc
Context: European mysticism was not dead at the time the United States of America was founded. The hand of the mysteries controlled in the establishment of the new government for the signature of the mysteries may still be seen on the Great Seal of the United states of America. Careful analysis of the seal discloses a mass of occult and Masonic symbols chief among them, the so-called American Eagle. … the American eagle upon the Great Seal is but a conventionalized phoenix... Not only were many of the founders of the United States government Masons, but they received aid from a secret and august body existing in Europe which helped them to establish this country for a peculiar and particular purpose known only to the initiated few. The Great Seal is the signature of this exalted body —unseen and for the most part unknown — and the unfinished pyramid upon its reverse side is a trestleboard setting forth symbolically the task to the accomplishment of which the United States Government was dedicated from the day of its inception.