Thirty years ago, Spike Lee’s explosive film Do the Right Thing arrived in theaters, in the wake of racially charged incidents that forever etched certain names and places into New York history: Eleanor Bumpurs; Bernie Goetz; Michael Stewart; Tawana Brawley; Howard Beach; the Central Park Five. When the Library of Congress selected Lee’s film for the National Film Registry, scholar David Sterritt noted that the “context in which Lee wrote Do the Right Thing” was “the long tradition of American racism.”

Perhaps. On the other hand, even a casual viewer of Do the Right Thing will notice that there’s a lot more to this particular Brooklyn block than, well, black and white. There are Korean store-owners and Puerto Rican stoop boys, Caribbean immigrants and Italian-American pizza slingers, the children of The Great Migration, and even a white guy who—despite his Larry Bird jersey—was “born in Brooklyn.”

It is with such messy and complicated American realities in mind that we read Daniel Okrent’s important new book. Its title refers to a nasty anti-immigrant poem by Thomas Bailey Aldrich, published in the august Atlantic Monthly in 1892—the very same year Ellis Island officially opened. Aldrich’s verses (“Wide open and unguarded stand our gates, / And through them presses a wild motley throng /... In street and alley what strange tongues are loud, / Accents of menace alien to our air...”) reflect the profound nativist sentiment of an era when as many as a million immigrants were entering the U.S. annually. The newcomers—largely Catholic and Jewish immigrants from central and eastern Europe—terrified the Protestant American establishment, particularly what Okrent calls the “Brahmin intelligentsia.” These were men like one-time U.S. Senator Henry Cabot Lodge, who wrote in 1891 that it was time to “guard our civilization against an infusion which seems to threaten deterioration,” or Boston school committee member Joe Lee, who declared “the Catholic Church a great evil,” and feared Europe was being “drained of Jews—to its benefit no doubt but not ours.”

The broader arc of The Guarded Gate traces the slow but steady merger of this long-standing American nativism with something new: scientific racism.

Okrent, best known as the first public editor of the New York Times, and the author of lively popular histories about Prohibition and Rockefeller Center, acknowledges his own personal connection to this material. His maternal grandfather, a physician, emigrated from Romania in 1922, managing “to slip in before the gates clanged shut two years later.” Consequently, Okrent confesses that he “can’t claim spotless objectivity as I tell the fateful story of how a perverse form of ‘science’ gave respectability to the drastic limits imposed on the number of Jews, Italians, Greeks, Poles, and various other eastern and southern Europeans seeking to come to America between 1924 and 1965.” The Guarded Gate also explores the role Okrent’s own publisher played in spreading many of this era’s more heinous ideas: the 1916 publication of Madison Grant’s seminal book, The Passing of the Great Race, made Charles Scribner’s Sons “effectively the official publisher of the scientific racism movement,” he writes.

The story of this “perverse science” is terrifying and complex, with a sprawling cast of characters, and Okrent’s narrative occasionally feels a touch bumpy, zigzagging back and forth through decades, with characters disappearing and reappearing. Overall, though, The Guarded Gate exerts a chilling power. One would be hard-pressed to exaggerate either the breadth or the intensity of the anti-immigrant animus Okrent chronicles. Cabot Lodge and others insisted that the era’s immigrants were “far removed in thought and speech and blood from the men who have made this country what it is.” And it wasn’t just the Brahmins. The editors of the Nation worried about the “foreign vote,” the New York Times feared the scheming of a “secret Polish society” in Pennsylvania, and a mob in New Orleans was so blinded by rage they lynched eleven Italians in 1891.

Not content with vilifying immigrants whose misfortune it was to be impoverished devotees of minority religions, the nativists of the day were fired up by thinkers like Edward A. Ross, who rose to prominence, Okrent writes, via articles and books “expressing his belief that many of the immigrants coming into the United States early in the twentieth century were members of ‘the lower races’—in truth, scarcely human.” Once a scientific rationale for nativism was established, it was only a matter of time before the political class responded—with the notorious Johnson-Reed Act of 1924, which targeted what our current president might call the “shithole countries” of the day, radically reducing Catholic and Jewish immigration to the U.S. “America of the Melting Pot Comes to an End,” the New York Times blared in April of 1924.

The story doesn’t end there. Okrent’s is just the latest book—others include Hitler’s American Model by James Q. Whitman, and Hitler’s American Friends by Bradley W. Hart—to highlight the significant contribution made by American eugenicists to what would become the Nazis’ Final Solution. (Okrent also notes that the Johnson-Reed Act deprived thousands a place of refuge from the Nazis.) The Guarded Gate closes with a nod to the immigration reforms of 1965, which flung open America’s gates once more.

Whether that was a good thing is a big part of our present political dilemma, and you can’t read this book without today’s rancorous debate over immigration in mind. Okrent’s conclusion begs another important question: What, if anything, actually connects yesterday’s immigrants with today’s? Given that tens of millions of Americans trace their roots back to the marginalized immigrants Okrent writes about, that question would seem to hold obvious significance. Yet prominent historians haven’t engaged much with the long-term legacy of Ellis Island. Jill Lepore’s recent bestselling 960-page survey of U.S. history, These Truths, dedicates fewer than a dozen pages to Catholic and Jewish immigration. Lepore’s book—like Howard Zinn’s beloved A People’s History of the United States—makes not a single reference to Ellis Island.

If there is so little to say about these folks, how can we possibly expect to make sense of why so many grandchildren of Ellis Island immigrants voted for a president—himself also the grandchild of an immigrant—whose language echoes 1920s eugenicists, and who at campaign rallies gleefully quotes an abhorrent anti-immigrant song called “The Snake”? Why have so many children of yesterday’s powerless lined up behind today’s powerful?

Until we confront these messy, complicated questions, whenever we see the next much-hyped movie or TV show about tensions between Ellis Island’s offspring and African-Americans—think the Oscar-winning melodrama Green Book, or Showtime’s new show City on a Hill, or David Chase’s forthcoming Sopranos prequel, set during the Newark riots—expect it to be discussed as, well, just another black-and-white movie.

The Guarded Gate

Bigotry, Eugenics, and the Law That Kept Two Generations of Jews, Italians, and Other European Immigrants Out of America

Daniel Okrent

Scribner, $32, 496 pp.