As most border residents will concede, the Rio Grande is a relatively modest stream, neither great nor grand compared to, say, the Mississippi or the Nile. A latter-day George Washington would have no trouble hurling a silver dollar from one bank to the other.

To hear border-security obsessives tell it, though, the Rio Grande is a veritable River Styx, the dreadful boundary between Earth and the fifth circle of Hell (to borrow from Dante). For President Donald Trump's political base, it's better to wall the river off, politicize and militarize it, than risk death, danger and contamination from the frightening other side.

What the would-be barrier builders are reluctant to acknowledge are the historic ties - cultural, economic and familial - that vault the river, that strengthen and enrich both the United States and Mexico.

Of course, we need to protect our borders. We must combat Mexican drug cartels, human traffickers and other dangers, and, yes, we need to curtail undocumented immigration. But to actively work to cut vital ties that bind the people of neighboring nations, whether it's decimating NAFTA, undercutting the Deferred Action for Childhood Arrivals program or enforcing anti-sanctuary city legislation, makes little sense. Whether it's President Trump's ill-informed border bluster or White House adviser Steve Miller's dark "America First" dreams, anti-immigrant efforts hurt this nation.

Consider, for example, Houston's need for labor in the wake of Hurricane Harvey. Even before the hurricane had its way with this city, 69 percent of Texas contractors were having difficulty finding qualified people to hire, as Todd Hitt, CEO of a Virginia-based private equity firm, noted in the Washington Post recently.

An estimated 200,000 Houston homes need extensive work or complete reconstruction. "Who will build these houses?" Hitt asks. "What about the commercial infrastructure and public schools, highways and bridges that also sustained so much damage?"

As Hitt points out, we're facing a nationwide problem, one that Harvey merely exacerbated here in southeast Texas. According to the National Association of Home Builders, 77 percent of U.S. builders can't find enough people for their framing teams. Sixty-one percent can't find enough drywall installation workers. The number of construction jobs available in the United States rose in June and increased again in July.

Hitt echoes a warning local construction-company owner Stan Marek made in the Chronicle last month. "Before Harvey, we were facing an extreme shortage of workers," he said. "I don't know where we're going to get the workers, legal or undocumented, to rebuild our city."

Workers who are living in the U.S. without documentation are estimated to constitute half the state's construction workforce and are vulnerable to abuse and exploitation without legal recourse, Marek said.

Harvey underscores the need to fix our broken immigration system - if, that is, Congress and the president are interested in solutions rather than scapegoating. We're trying to function with a deeply flawed immigration model, circa 1986. Doesn't it make more sense to calibrate labor supply with demand by reworking our visa system? Shouldn't laborers with skills we desperately need have opportunities to legally work in this country, as long as they're not displacing Americans?

As U.S. Sen. Jeff Flake, R-Ariz., pointed out in a New York Times opinion piece, our system also should make room for those whose primary skill is the willingness to do unglamorous and often excruciating work - "moving sprinkler pipes, digging ditch, chopping hay or keeping a broken-down feed truck running for just one more year."

In Flake's words, "these Americans by choice are some of the most inspiring Americans of all."

Houston needs workers. In the midst of our need, it's only fair that we're at the forefront of efforts to fix a flawed immigration system. We have an obligation to bring the undocumented out of the shadows.