Ken Burns’ ‘The U.S. and the Holocaust’ examines a question that haunts us still: Why didn’t we do more?

I’m still reeling from “The U.S. and the Holocaust,” still pondering its complex portrait of national inaction, and thinking more than ever about Jewish theologian Abraham Joshua Heschel’s observation, “Few are guilty, but all are responsible.”

This piercing, must-see documentary asks the hard questions that have haunted many Americans in the decades since World War II. What was happening here while multitudes — including two-thirds of Europe’s estimated 9 million Jews — were being systematically forced into ghettos and camps, starved, tortured, and murdered there? Did American politicians and citizens know of the brutal persecution of Jews and turn a cold shoulder? Was President Franklin D. Roosevelt, who famously refused a ship containing 900 destitute Jewish refugees in 1939, a coward? Were we indifferent, and complicit?

And, most difficult of all, as xenophobia, antisemitism, white supremacy, and fascism continue to dog the promise and the premise of this country, have we learned anything from our inadequate response to Hitler’s genocide?

One of the strengths of the PBS three-parter, which airs Sunday, Tuesday, and Wednesday nights at 8 on GBH 2, is that it provides us with the kinds of in-depth answers to all these questions that defy easy summarizing. “The U.S. and the Holocaust,” which is from filmmakers Ken Burns, Lynn Novick, and Sarah Botstein, is not a finger-pointing attack so much as a detailed explication filled with nuance and context. There is a plethora of reasons we did not allow many refugees into this country, even while we ultimately went to war against the sources of their torment, Hitler and the Nazis. Those reasons don’t erase the fact that we failed so many desperate victims — 75 percent of the 6 million murdered Jews were already dead by the time we landed in France in 1944 — but they help us to understand why.

In an image provided by Library of Congress, via PBS, an immigrant family looks at the Statue of Liberty from Ellis Island in New York in 1930, as seen in"The U.S. and the Holocaust."LIBRARY OF CONGRESS, VIA PBS/NYT

Some of the reasons predate the question of admitting refugees who were fleeing Hitler, and they include the economic fears triggered by the Great Depression. The film explores the theory of eugenics — selective breeding of the human population — that rose in the United States in the late 19th and early 20th centuries and went on to captivate the likes of Teddy Roosevelt and Helen Keller. That false perspective led many Americans to see immigrants as fouling the effort to create some kind of superior race. We learn about the strict anti-immigration law (the Johnson-Reed Act) passed in 1924 that included a tiny quota for immigrants from Eastern Europe. And, of course, racism had long been entrenched here, not least of all toward Blacks and indigenous people, to the point where Hitler turned to America’s treatment of them — including Jim Crow laws — as models for his efforts to disenfranchise Jews.

There were plenty of American newspaper stories, even before the war began, about what Hitler was up to — “The U.S. and the Holocaust” makes that quite clear. At one point, we hear Edward R. Murrow delivering a 1942 radio report noting, “Millions of human beings, most of them Jews, are being gathered up with ruthless efficiency and murdered.” But some felt that if American Jews made it into an issue, it would somehow make life worse for European as well as American Jews. FDR considered Hitler a “madman,” and after Kristallnacht in 1938, he removed the American ambassador to Berlin, but the public — many of them fueled by powerful antisemitic voices including radio preacher Father Charles Coughlin and aviator Charles Lindbergh — as well as Congress, were not pushing him to offer sanctuary. He believed that defeating the Axis was the answer, and he also believed that it was important to deemphasize the Jews, lest the troops not fight as hard.

Prisoners of the Buchenwald concentration camp, as seen in "The U.S. and the Holocaust." The writer Elie Wiesel can be seen in the second row, seventh from left.NATIONAL ARCHIVES AND RECORDS ADMINISTRATION, VIA PBS/NYT

I hope I’m not making the documentary sound dry. The scholarly elements are compelling, and delivered by a series of articulate historians, but they are surrounded by personal stories that, as you might expect, have a resounding emotional impact. Interestingly, the filmmakers go over the story of Anne Frank and her family once again — but with a striking emphasis on her father Otto’s efforts to come to the United States. We hear other frustrating stories of failed attempts to get here, including one from writer Daniel Mendelsohn, who describes his great-uncle’s struggle to come with his family, six names on a 10-year-long waiting list. For every piece of historical analysis, there is a detailed and moving personal story.

As “The U.S. and the Holocaust” toggles back and forth between events here and in Europe, it includes enough footage from the camps to keep you grounded in what was at stake in all of this talk of refugees. Some of the footage, we’re told, was taken by Nazis so they could use it to show off later. At one point, we see a long line of starving Jews looking ahead to see they’re moving toward a firing squad. It’s impossible to know what they’re feeling, just as it is impossible to know how the survivors feel as we see a cantor singing to them in their just-liberated camp. These and other carefully deployed pieces of footage give the film all the visceral power it needs.

“The U.S. and the Holocaust” will break your heart and challenge your faith. It tells its nightmare story with eloquence, insight, rigor, and compassion, an unflinching report from master storytellers at the height of their powers.

THE U.S. AND THE HOLOCAUST

On: GBH 2. Sunday, Tuesday, and Wednesday nights, 8-10 p.m.

Matthew Gilbert can be reached at matthew.gilbert@globe.com. Follow him @MatthewGilbert.