IN SOMBER tones, the top elected official in Virginia’s second-largest locality expresses his deep concern about the plight of thousands of undocumented minors crossing the U.S.-Mexico border — some of whom are being temporarily housed in his own jurisdiction. He says he’s very worried, not least about their unknown “medical needs.” The children, he says, have his “personal sympathies.”

And by the way, adds Corey A. Stewart, the chairman of Prince William County’s Board of Supervisors, they all should be deported.

Mr. Stewart, who rose to prominence in Northern Virginia politics as an immigrant-basher, is up to his old tricks of hyperbole and misinformation. His main concern, he insists, is to “protect” the county from the onslaught of immigrants who, he opined in an interview with WAMU-FM, will impose “a burden on our community, on the school system and the social services system as well.”

Fewer than 100 undocumented minors are housed in Prince William, on the campus of Youth for Tomorrow, a nonprofit group and school. They undergo a health screening before arriving; there have been no credible reports of any unusual health problems. The children won’t remain long; the average stay at such facilities is 35 days before they are placed with sponsors — typically parents or relatives — who are likely to be elsewhere.

Moreover, facilities housing underage migrants will impose very little burden on localities. If the migrants need schooling, health care or other services while at the facilities, which are run by contractors, the federal government is responsible for providing them. While they are housed at the facility, none of the youths will be enrolled in local public schools.

This July 14, 2014 photo shows graffiti on the side of a former Army Reserve Center in Westminster, Md. (Christian Alexandersen/AP)

A modest number of the undocumented children at the facility in Prince William could end up as county residents, placed with relatives, while they await adjudication and possible deportation. We’re confident that Prince William, whose school system is one of the 40 biggest in the nation, can absorb them.

Meanwhile, a growing number of officials of both parties are seeking political advantage from the immigration crisis, in some cases crassly. In Maryland, Gov. Martin O’Malley, a Democrat with presidential aspirations, has staked out a more-caring-than-thou stance on the left — even as he privately tried to derail plans for a facility for the migrants in a conservative part of the state. In Texas, one town declared its opposition to opening any shelters even though the federal government had no plans to do so.

As for Mr. Stewart, he says he hopes citizens who object to the presence of the immigrants won’t protest or otherwise harass the kids. Yet by inflaming the issue with misinformation, he increased the chances of just such an outcome.

The government should discourage unaccompanied minors from making the perilous trek north to enter this country illegally. But the law provides safeguards, temporary settlement and procedures for adjudicating the cases of those already here. The United States has a legal and moral obligation to treat them humanely, and local officials should refrain from inciting passions against vulnerable children.