In raising the example of Operation Wetback, Trump attempts to make the case that deporting 11 to 12 million unauthorized immigrants from the United States is possible, no matter what the skeptics say.
"He's saying, 'We've done it before when we deported 1 million people in one year.' So in his mind, it kind of makes sense," said Luis Plascencia, an Arizona-based scholar and an expert on Mexican immigration, Mexico-U.S. borderlands and citizenship.
The popular narrative, one accepted by many historical scholars, is that 1 million people of Mexican descent, including many U.S. citizens, were removed from the United States during Operation Wetback in 1954.
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But Plascencia and a smaller number of scholars say the 1 million figure was for the entire fiscal year, not just the mere seven weeks Operation Wetback lasted.
Plascencia and others contend that a far smaller number of people were deported - perhaps 33,000 to 74,000 people. Plascencia told NBC News the difficulty pinpointing the number lies in the fact that the government did not report the number of people deported, only those apprehended. In Texas, says Plascencia, it's possible that the vast majority of the estimated 41,000 people apprehended in July, 1954 were allowed to stay in the country, merely reclassified as bracero workers.
So how did the 1 million figure gain traction? Plascencia says it was the commissioner of the Immigration and Naturalization Service, Gen. Joseph May Swing, who used the figure for the entire 1954 fiscal year.
"I think he wanted to show success," Plascencia said. "When you're pressured to show success you may fudge a little bit."