People leave the places where they lack safety and opportunity, and they go, sometimes at great risk, to where they have hope of finding those things. This eternal reality is often shunted aside in debates about immigration policy.

The latest chapter in this long story has been building over several weeks on the nation's southern border. More than 4,000 children are in the custody of U.S. Customs and Border Protection, enduring overcrowding and processing delays as they await transfer to the Department of Health and Human Services and eventual placement with family members or other sponsors.

The children have presented themselves at the border seeking asylum. Many have arrived alone. Most are from Central America, where there is persistent economic hardship and violence. Homeland Security Secretary Alejandro Mayorkas said this week that 80% of them have a relative in the U.S. and 40% have a parent here.

Critics of President Joe Biden say this influx is a result of his having essentially hung out a banner reading: "Y'all come." They say the conditions warrant the kind of derision the Trump administration received when it kept migrant children within chain-link partitions. House Minority Leader Kevin McCarthy, who led a Republican delegation to Texas this week, squarely called it the "Biden border crisis."

As politically opportunistic as that extended assessment is, and as inaccurate or incomparable as it is on several counts, it has one element of truth: If children are being treated poorly, that can't be abided.

But is this a "Biden" crisis? To the extent that he's now president, yes, he owns it. As far as his being the primary cause, not so. Conditions in the Northern Triangle countries of Central America have produced waves of asylum-seekers for years. And a reversion to the mean on U.S. policies was inevitable after four years of draconian efforts by the administration of President Donald Trump to repel migrants.

Biden indeed has promised comprehensive immigration reform, aspects of which have public support, but the border is still sealed to most who want to come. The administration says it will take time to sort out. Still, it failed to fully anticipate the effects of evolving policies, not to mention the promise that those attempting to migrate might perceive in them, and at least initially was slow to respond to the issues that arose.

Specifically, Biden determined that the U.S. would receive unaccompanied children seeking asylum. The Trump administration had been turning them away. Biden has retained Trump's policy of expelling adult migrants. That's led to a concurrent buildup on the Mexico side of the border that officials there are ill-equipped to handle. All this amid a pandemic, which has been a factor in the capacity issues and processing delays.

The administration has been reluctant to call the situation a crisis, but in the last week it has taken crisis-style steps such as opening temporary overflow facilities and tapping the Federal Emergency Management Agency for help with the young migrants' basic needs. It also has tried to send the message, as best as it can through the White House megaphone, that migrants should stay put for now. Biden reiterated it Tuesday on TV: "I can say quite clearly: Don't come. ... [W]e're in the process of getting set up. Don't leave your town or city or community."

Well, a president can ask, but the larger forces remain.

The Star Tribune Editorial Board has long supported comprehensive immigration reform, and for an equally long time the board has been exasperated with the lack of progress in Congress. Some lawmakers have hit upon the idea of breaking off bits of reform to get things moving.

This week, the House approved two paths to citizenship or legal status: the American Dream and Promise Act, which would help those brought to the U.S. as children, and the Farm Workforce Modernization Act, for farmworkers who are in the country illegally. The votes were basically along party lines. The fate of these bills in the Senate, where 10 Republican votes are needed to defy a filibuster, barring a deus ex machina on that subject, is worrisome. The outcome will give an early indication of whether collaborative action is possible.

As needed as these steps are in any case, they won't help with the immediate issue of asylum-seekers from places like Guatemala, El Salvador and Honduras. For that, Biden plans $4 billion in development aid. That won't get a universal embrace, either, but U.S. inattention to conditions in those countries is neither honorable nor practical. The fundamental causes of migration are an American concern in the broadest sense of the geographic term.