“Let every man honor and love the land of his birth and the race from which he springs and keep their memory green. It is a pious and honorable duty. But let us have done with British-Americans and Irish-Americans and German-Americans, and so on, and all be Americans…If a man is going to be an American at all let him be so without any qualifying adjectives; and if he is going to be something else, let him drop the word American from his personal description.”

1910s, Address to the Knights of Columbus (1915)
Context: The one absolutely certain way of bringing this nation to ruin, of preventing all possibility of its continuing to be a nation at all, would be to permit it to become a tangle of squabbling nationalities, an intricate knot of German-Americans, Irish-Americans, English-Americans, French-Americans, Scandinavian-Americans or Italian-Americans, each preserving its separate nationality, each at heart feeling more sympathy with Europeans of that nationality, than with the other citizens of the American Republic. The men who do not become Americans and nothing else are hyphenated Americans; and there ought to be no room for them in this country. The man who calls himself an American citizen and who yet shows by his actions that he is primarily the citizen of a foreign land, plays a thoroughly mischievous part in the life of our body politic. He has no place here; and the sooner he returns to the land to which he feels his real heart allegiance, the better it will be for every good American. There is no such thing as a hyphenated American who is a good American. The only man who is a good American is the man who is an American and nothing else.

1910s, Letter to the American Defense Society (1919)
Context: In the first place we should insist that if the immigrant who comes here in good faith becomes an American and assimilates himself to us, he shall be treated on an exact equality with everyone else, for it is an outrage to discriminate against any such man because of creed, or birthplace, or origin. But this is predicated upon the man's becoming in very fact an American, and nothing but an American. If he tries to keep segregated with men of his own origin and separated from the rest of America, then he isn't doing his part as an American. There can be no divided allegiance here. Any man who says he is an American, but something else also, isn't an American at all. We have room for but one flag, the American flag, and this excludes the red flag, which symbolizes all wars against liberty and civilization, just as much as it excludes any foreign flag of a nation to which we are hostile. We have room for but one language here, and that is the English language, for we intend to see that the crucible turns our people out as Americans, of American nationality, and not as dwellers in a polyglot boarding-house; and we have room for but one soul loyalty, and that is loyalty to the American people.

§14
'Tis (2000)
Source: ' Tis: a Memoir
Context: Why is it the minute I open my mouth the whole world is telling me they're Irish and we should all have a drink? It's not enough to be American. You always have to be something else, Irish-American, German-American, and you'd wonder how they'd get along if someone hadn't invented the hyphen.

born in this century, tempered by war, disciplined by a hard and bitter peace, proud of our ancient heritage — and unwilling to witness or permit the slow undoing of those human rights to which this Nation has always been committed, and to which we are committed today at home and around the world.
The quote "Let the word go forth from this time and place, to friend and foe alike, that the torch has been passed to a new generation of Americans" is one of seven quotes inscribed on the walls at the gravesite of John F. Kennedy at Arlington National Cemetery. http://www.jfklibrary.org/Researchold/Ready-Reference/JFK-Miscellaneous-Information/Grave-Inscription.aspx One can see it inscribed on the walls at the gravesite of John F. Kennedy at Arlington National Cemetery.
1961, Inaugural Address

Our America (1881)

"What Is An American?" http://www.historyplace.com/speeches/ickes.htm (18 May 1941)

Americans have always known how to fight for their rights and their way of life. Americans are not afraid to fight. They fight joyously in a just cause.
"What Is An American?" http://www.historyplace.com/speeches/ickes.htm (18 May 1941)

1963, Civil Rights Address

2010s, 2016, Statement regarding the Khan family (1 August 2016)