The image of the United States as a melting pot was popularized by the 1908 play The Melting Pot.
The melting pot is a monocultural metaphor for a heterogeneous society becoming more homogeneous, the different elements "melting together" into a harmonious whole with a common culture or vice versa, for a homogeneous society becoming more heterogeneous through the influx of foreign elements with different cultural background with a potential creation of disharmony with the previous culture. Historically, it is often used to describe the assimilation of immigrants to the United States. The melting-together metaphor was in use by the 1780s. The exact term "melting pot" came into general usage in the United States after it was used as a metaphor describing a fusion of nationalities, cultures and ethnicities in the 1908 play of the same name.
The desirability of assimilation and the melting pot model has been reconsidered by proponents of multiculturalism, who have suggested alternative metaphors to describe the current American society, such as a mosaic, salad bowl, or kaleidoscope, in which different cultures mix, but remain distinct in some aspects.
In the 18th and 19th centuries, the metaphor of a "crucible" or "smelting pot" was used to describe the fusion of different nationalities, ethnicities and cultures. It was used together with concepts of the United States as an ideal republic and a "city upon a hill" or new promised land. It was a metaphor for the idealized process of immigration and colonization by which different nationalities, cultures and "races" (a term that could encompass nationality, ethnicity and race proper) were to blend into a new, virtuous community, and it was connected to utopian visions of the emergence of an American "new man". While "melting" was in common use the exact term "melting pot" came into general usage in 1908, after the premiere of the play The Melting Pot by Israel Zangwill.
The first use in American literature of the concept of immigrants "melting" into the receiving culture are found in the writings of J. Hector St. John de Crevecoeur. In his Letters from an American Farmer (1782) Crevecoeur writes, in response to his own question, "What then is the American, this new man?" that the American is one who "leaving behind him all his ancient prejudices and manners, receives new ones from the new mode of life he has embraced, the government he obeys, and the new rank he holds. He becomes an American by being received in the broad lap of our great Alma Mater. Here individuals of all nations are melted into a new race of men, whose labors and posterity will one day cause great changes in the world."
...whence came all these people? They are a mixture of English, Scotch, Irish, French, Dutch, Germans, and Swedes... What, then, is the American, this new man? He is either an European or the descendant of an European; hence that strange mixture of blood, which you will find in no other country. I could point out to you a family whose grandfather was an Englishman, whose wife was Dutch, whose son married a French woman, and whose present four sons have now four wives of different nations. He is an American, who, leaving behind him all his ancient prejudices and manners, receives new ones from the new mode of life he has embraced, the new government he obeys, and the new rank he holds.... The Americans were once scattered all over Europe; here they are incorporated into one of the finest systems of population which has ever appeared.
— J. Hector St. John de Crevecoeur, Letters from an American Farmer
In 1845, Ralph Waldo Emerson, alluding to the development of European civilization out of the medieval Dark Ages, wrote in his private journal of America as the Utopian product of a culturally and racially mixed "smelting pot", but only in 1912 were his remarks first published. In his writing, Emerson explicitly welcomed the racial intermixing of whites and non-whites, a highly controversial view during his lifetime.
A magazine article in 1876 used the metaphor explicitly:
The fusing process goes on as in a blast-furnace; one generation, a single year even—transforms the English, the German, the Irish emigrant into an American. Uniform institutions, ideas, language, the influence of the majority, bring us soon to a similar complexion; the individuality of the immigrant, almost even his traits of race and religion, fuse down in the democratic alembic like chips of brass thrown into the melting pot.
In his 1905 travel narrative The American Scene, Henry James discusses cultural intermixing in New York City as a "fusion, as of elements in solution in a vast hot pot".
The exact term "melting pot" came into general usage in the United States after it was used as a metaphor describing a fusion of nationalities, cultures and ethnicities in the 1908 play of the same name, first performed in Washington, D.C., where the immigrant protagonist declared:
Understand that America is God's Crucible, the great Melting-Pot where all the races of Europe are melting and re-forming! Here you stand, good folk, think I, when I see them at Ellis Island, here you stand in your fifty groups, your fifty languages, and histories, and your fifty blood hatreds and rivalries. But you won't be long like that, brothers, for these are the fires of God you've come to—these are fires of God. A fig for your feuds and vendettas! Germans and Frenchmen, Irishmen and Englishmen, Jews and Russians—into the Crucible with you all! God is making the American.
In The Melting Pot (1908), Israel Zangwill combined a romantic denouement with an utopian celebration of complete cultural intermixing. The play was an adaptation of William Shakespeare's Romeo and Juliet, set in New York City. The play's immigrant protagonist David Quixano, a Russian Jew, falls in love with Vera, a fellow Russian immigrant who is Christian. Vera is an idealistic settlement house worker and David is a composer struggling to create an "American symphony" to celebrate his adopted homeland. Together they manage to overcome the old world animosities that threaten to separate them. But then David discovers that Vera is the daughter of the Tsarist officer who directed the pogrom that forced him to flee Russia. Horrified, he breaks up with her, betraying his belief in the possibility of transcending religious and ethnic animosities. However, unlike Shakespeare's tragedy, there is a happy ending. At the end of the play the lovers are reconciled.
Reunited with Vera and watching the setting sun gilding the Statue of Liberty, David Quixano has a prophetic vision: "It is the Fires of God round His Crucible. There she lies, the great Melting-Pot—Listen! Can't you hear the roaring and the bubbling? There gapes her mouth, the harbor where a thousand mammoth feeders come from the ends of the world to pour in their human freight". David foresees how the American melting pot will make the nation's immigrants transcend their old animosities and differences and will fuse them into one people: "Here shall they all unite to build the Republic of Man and the Kingdom of God. Ah, Vera, what is the glory of Rome and Jerusalem where all nations and races come to worship and look back, compared with the glory of America, where all
races and nations come to labour and look forward!"
Zangwill thus combined the metaphor of the "crucible" or "melting pot" with a celebration of the United States as an ideal republic and a new promised land. The prophetic words of his Jewish protagonist against the backdrop of the Statue of Liberty allude to Emma Lazarus's famous poem The New Colossus (1883), which celebrated the statue as a symbol of American democracy and its identity as an immigrant nation.
Zangwill concludes his play by wishing, "Peace, peace, to all ye unborn millions, fated to fill this giant continent—the God of our children give you Peace." Expressing his hope that through this forging process the "unborn millions" who would become America's future citizens would become a unified nation at peace with itself despite its ethnic and religious diversity.