Gregory Bull, Associated Press
FILE - In this June 22, 2016, file photo, Border Patrol agent Eduardo Olmos walks near the secondary fence separating Tijuana, Mexico, background, and San Diego in San Diego.

Since President Donald Trump took office, illegal crossings along the southwest border are down — way down.

And, although myriad factors affect immigration trends in the U.S., it’s hard not to conclude that Trump’s barbed-wire wall of rhetoric is working.

Last week, the U.S. secretary of Homeland Security, John F. Kelly, announced that in the past two months unlawful crossings have dropped 40 percent.

These numbers represent a dramatic swing in trends. Since 2000, statistics from Customs and Border Protection typically show a seasonal uptick (rather than a decline) in illegal crossings during this time of year.

Not only does it appear that Trump’s wall of words is effective, but it’s also free. So should Trump and Americans ramp up the rhetoric? There’s reason for caution — after all, unbridled bellicosity has costs, and scapegoating (even if implicitly) has never helped America truly succeed.

The nation’s history has proved over and over that regardless of immigration policies or other circumstances, personal responsibility, strong families, churches, communities, schools and better personal choices, along with a collective culture of burden sharing and industry, are the best medicine for combating intergenerational ills.

J.D. Vance’s best-selling memoir, “Hillbilly Elegy,” details some of the plagues facing white working-class families in America. During the 2016 campaign, Vance commented that, in his opinion, Trump’s rhetoric was in many ways “another opioid” for the white worker.

It serves as “something that will take the pain away ... but at the end of the day the problems are still going to be there."

He continued: “You can’t just blame other people.”

While undocumented aliens present an unquestionable security problem, tacitly blaming them for a flagging white working class provides only a placebo for treating the root causes. And sadly, the rhetoric can, by fostering a sense of entitlement and helplessness, sometimes make symptoms worse.

Now, to be clear, it’s essential for any nation to secure its border, to keep its citizenry safe and to ameliorate the social ravages of rapid economic disruption. Trump deserves praise for his sincere efforts to secure the nation and lift forgotten segments of society.

Yet, as if taken straight off the prophetic pages of F. Scott Fitzgerald, Trump’s fervor could unintentionally provide cover, and perhaps even fodder, for a burgeoning class of modern-day Tom Buchanans:

“The idea is if we don’t look out the white race will be — will be utterly submerged. It’s all scientific stuff; it’s been proved,” Buchanan says in Fitzgerald’s novel "The Great Gatsby." "It’s up to us, who are the dominant race, to watch out or these other races will have control of things.”

Buchanan says later: “This idea is that we’re Nordics. I am, and you are, and ... we’ve produced all the things that go to make civilization...”

Apart from being factually wrong, such latent white protectionism is dangerous —even when it doesn’t overtly foment racial animus, it’s corrosive to a culture of meritocracy, industry, empathy and sacrifice. It leaves only entitlement and enmity in its wake.

Tom Buchanan believes ancestry and social station entitle him to wealth, power and, as the book details, hedonistic indulgence. Yet, as Fitzgerald’s narrative points out so well, unmoored from virtue, the elixir of entitlement is really just a sign of decline and decay.

By implicitly blaming problems on others, rather than first looking introspectively at our working-class ruins, is to wash our hands rather than confront challenges and search for solutions.

There are, as mentioned, reasons for optimism about Trump, even with very real rhetorical risks. But if Trump wants to help the Rust Belt and declining America (and I believe he does), helping individuals make positive personal choices is just as important as shovel-ready jobs, better trade deals and fewer illegal immigrants.

Along with bloviating about border walls, Trump must also spend equal time finding ways to help rebuild families and faith. Jobs are a part of it, but so too is culture and community.

Through the novel’s narrator, Fitzgerald describes Buchanan and his wife, Daisy, as “careless people” who “smashed up things” and “retreated back into their money or their vast carelessness.”

Things are smashed for far too many Americans. The solution can no longer be careless rhetoric and more cash. We must return to each other. We need to tear down the social walls around us, regardless of whether we build a new one on the southern border.