“The American people should itself do these things for the immigrants. If we leave the immigrant to be helped by representatives of foreign governments, by foreign societies, by a press and institutions conducted in a foreign language and in the interest of foreign governments, and if we permit the immigrants to exist as alien groups, each group sundered from the rest of the citizens of the country, we shall store up for ourselves bitter trouble in the future.”

2010s, Address to the United States Congress

Preface
Sackett's Land (1974)
Context: We are all of us, it has been said, the children of immigrants and foreigners — even the American Indian, although he arrived here a little earlier. What a man is and what he becomes is in part due to his heritage, and the men and women who came west did not emerge suddenly from limbo. Behind them were ancestors, families, and former lives. Yet even as the domestic cattle of Europe evolved into the wild longhorns of Texas, so the American pioneer had the characteristics of a distinctive type.
Physically and psychologically, the pioneers' need for change had begun in the old countries with their decision to migrate. In most cases their decisions were personal, ordered by no one else. Even when migration was ordered or forced, the people who survived were characterized by physical strength, the capacity to endure, and not uncommonly, a rebellious nature.
History is not made only by kings and parliaments, presidents, wars, and generals. It is the story of people, of their love, honor, faith, hope and suffering; of birth and death, of hunger, thirst and cold, of loneliness and sorrow. In writing my stories I have found myself looking back again and again to origins, to find and clearly see the ancestors of the pioneers.

Interviewed in Aftenposten (13 November 2005) http://www.aftenposten.no/nyheter/iriks/politikk/article1155154.ece

1910s, Address to the Knights of Columbus (1915)
Context: The foreign-born population of this country must be an Americanized population. No other kind can fight the battles of America either in war or peace. It must talk the language of its native-born fellow-citizens; it must possess American citizenship and American ideals. It must stand firm by its oath of allegiance in word and deed and must show that in very fact it has renounced allegiance to every prince, potentate, or foreign government. It must be maintained on an American standard of living so as to prevent labor disturbances in important plants and at critical times. None of these objects can be secured as long as we have immigrant colonies, ghettos, and immigrant sections, and above all they cannot be assured so long as we consider the immigrant only as an industrial asset. The immigrant must not be allowed to drift or to be put at the mercy of the exploiter. Our object is not to imitate one of the older racial types, but to maintain a new American type and then to secure loyalty to this type. We cannot secure such loyalty unless we make this a country where men shall feel that they have justice and also where they shall feel that they are required to perform the duties imposed upon them. The policy of 'Let alone' which we have hitherto pursued is thoroughly vicious from two standpoints. By this policy we have permitted the immigrants, and too often the native-born laborers as well, to suffer injustice. Moreover, by this policy we have failed to impress upon the immigrant and upon the native-born as well that they are expected to do justice as well as to receive justice, that they are expected to be heartily and actively and single-mindedly loyal to the flag no less than to benefit by living under it.

2010s, 2016, August, Speech in Jackson, Mississippi (August 24, 2016)

2009, Speech: The Socio-Economic Peace Program of Senator Francis Escudero

All for Australia (1984)

This misattribution seems to have originated as improper quoting of an actually site-created preamble to an online page of Jefferson's quotes or paraphrases at the site Family Guardian https://famguardian.org/index.htm — self described as a "Nonprofit Christian religious ministry dedicated to protecting people and families from extortion, persecution, exploitation, socialism, divorce, crime, and sin." Among the preambles to their pages, these remarks summarizing the site creators' assessments on "Immigration Policy" https://famguardian.org/subjects/politics/thomasjefferson/jeff1280.htm for their page of Jefferson's statements regarding the subject, have occasionally been wrongly copied and distributed in various internet articles and comments as if they were direct "quotes" of Jefferson, sometimes with spurious citations to specific documents, most commonly the source of the first actual quote citation on that page: an 1806 letter to Albert Gallatin. It should also be noted that even the provided "quotes" at this site are not absolutely reliable, as on their index page for quotes of Thomas Jefferson on Politics & Government https://famguardian.org/subjects/politics/thomasjefferson/jeffcont.htm they indicate that some of the "quotes" they use are modernized and "generalized" (or in other words: paraphrased) in ways which diverge slightly from literal quotations of the original sources cited.
Misattributed

" A Second Half Life" (1991), p. 324
It All Adds Up (1994)