A century ago, Israel Zangwill popularized the term in his play, “The Melting Pot.” New York has evolved into a greater crucible of race and ethnicity today than it was back then, but the city also remains very much a mosaic — a variegated montage of neighborhoods in which certain groups predominate.

In a month or so, the 2010 census will most likely confirm a record high in the city’s foreign-born population. American Community Survey data released last month revealed a striking metamorphosis during the last decade. Traditional ethnic enclaves sprawled amoeba-like into adjacent communities. Once monolithic tracts of white and black and native-born residents have become bespeckled with newcomers.