Eighty years ago last month, the S.S. St. Louis entered American waters.

The liner carried more than 900 Jewish refugees fleeing Nazi persecution, hoping to find a haven across the Atlantic. Passengers had purchased landing certificates and transit visas issued by the Cuban government, and most planned to wait in Cuba while their U.S. visa applications were processed. But the Cuban government was roiled by political infighting and fearmongering that Jewish refugees might be communists. Officials turned nearly all of the passengers away.

The St. Louis sailed to Florida, coming so close to U.S. shores that passengers could see the lights of Miami, as one survivor noted in an oral history kept by the U.S. Holocaust Memorial Museum. Passengers cabled President Franklin D. Roosevelt to ask for refuge but never heard back.

America -- where similar nativist and anti-Semitic rhetoric had infected the public -- also turned the refugees away. The State Department directed desperate refugees to "await their turns on the waiting list and qualify for and obtain immigration visas before they may be admissible into the United States."

The ship returned to Europe, where a handful of countries had agreed to take in the passengers. But many ultimately fell into German hands, and a quarter of the ship's original manifest died during the Holocaust.

It's hard not to think about such shameful episodes of U.S. history amid our current treatment of the huddled masses yearning to breathe free. Our rejection of innocents seeking refuge from persecution, based on excuses that they might become an economic burden or national security threat. Our disingenuous claims that people need only to follow the rules and get in line.

Last week, while Americans continued our endless debate about whether President Trump's bigoted rhetoric put immigrants in danger, his actions should have left no doubt. Among a litany of other anti-immigrant measures, the administration announced that it was gutting the U.S. asylum system, effective immediately, by rejecting any new arrivals who had not first sought asylum in another country they passed through on their way.

This change violates both domestic and international law -- including an international pact set up partly to prevent another St. Louis -- and is being challenged in court. If allowed to stand, it will force thousands risking all to reach the U.S. border to return to dangerous conditions in their home countries or in Mexico.

Also last week, Politico reported that the administration is considering zeroing out refugee admissions from around the world next year. That includes Iraqi interpreters who put their lives on the line assisting U.S. forces, and whose visas we have already been appallingly slow to process. For this reason, then-Defense Secretary Jim Mattis reportedly opposed refugee cuts last year, fearing the consequences for national security.

There are other echoes, too, between our treatment of refugees today and in the 1930s, including presidential use of backdoor administrative actions to circumvent legislative debate. Back then, for instance, consular officials who were "under quota" -- who kept admissions below strict (racist) national-origin quotas set by Congress -- got letters of commendation under both Presidents Herbert Hoover and Roosevelt, according to American University history professor Alan Kraut.

There is, however, at least one key way that today's immigration policies differ from those in the dark period of the 1930s -- and, in fact, are arguably worse.

The immigration system in place then was structured not around compassion, or other abstract concepts such as morality or equity, but on a determination of which peoples were believed to be most economically and culturally advantageous to the United States. Our moral obligations to the world through asylum and refugee policy were only legally formalized in the postwar years, after the Holocaust (and the U.S. immigration system's complicity in it) had "shocked the conscience" of many Americans.

"We were in a sense making up for the mistakes we had made in the run-up to World War II," says Morris Vogel, a historian and president emeritus of the Lower East Side Tenement Museum.

In other words: Today, we know exactly what we're doing when we turn refugees away. Today, we know what happens when the "doors [are] closed" to a persecuted people, as White House senior adviser Jared Kushner's grandmother, a Holocaust survivor, put it in her own oral history. Today, we know the drive such people have to succeed in the United States despite their persecution.

U.S. policy toward displaced or persecuted peoples has never exactly been generous. But adjusted for the lessons that history now affords us, rarely has it been so deliberately stingy.

Catherine Rampell is a columnist for The Washington Post.