Rumors began circulating earlier this morning that the exception announced by Justin Trudeau on Monday on access into and out of Canada might not last long. Not long after reports emerged that the US and Canada had agreed in principle to close the longest unmilitarized border in the world, Donald Trump made it more or less official:

https://twitter.com/realDonaldTrump/status/1240271178692005889

Trudeau followed suit a few minutes ago:

WATCH LIVE: Canadian Prime Minister Justin Trudeau speaks about the coronavirus response, as Canada and the U.S. suspend non-essential travel at their border https://t.co/yMZlZ5gV1w pic.twitter.com/jHgUXJYCr5

— CBS News (@CBSNews) March 18, 2020

The U.S. and Canada have agreed to temporarily close their shared border to nonessential travel, President Donald Trump announced Wednesday as the two nations work to stem the spread of the coronavirus pandemic.

Both countries are eager to choke off the spread of the virus but also maintain their vital economic relationship. Canada relies on the U.S. for 75% of its exports. …

Truck drivers and Canadian snowbirds, who live in the U.S. for part of the year and are returning to Canada, are among those expected to get an exemption. Completely closing the border would cause severe economic damage to both the U.S. and Canada as the two economies are integrated. Much of Canada’s food supply comes from or via the U.S., and and 98% of its oil exports go to the U.S.

About 18% of American exports go to Canada.

Trudeau addressed the issue of returning Canadians in his announcement Monday, so that was likely already a settled issue. Truck drivers and support personnel for the trading relationship will be a trickier issue to settle. One would imagine that both countries will want testing to screen for COVID-19 to prevent any new transmissions. Otherwise, trade is too critical for both countries to stop it, but especially for Canada.

With people on both sides of the border hunkering down for the duration anyway, this may be more of a formality. The biggest issue now will be residents repatriating back home, which shouldn’t take long, and then whatever economic damage comes from the lack of exchange across the border. Since that will likely pale in comparison to the damage done by effectively sheltering in place the next few weeks, closing the border to non-essential traffic — but keeping trade going — makes a lot of sense.

It also makes political sense. Closed borders are making a public-policy comeback, according to this new international Ipsos poll:

A majority of people across 12 nations think the borders of their country should be closed until the coronavirus outbreak is contained, according to the latest Ipsos survey.

In a survey of 12,000 people across 12 major countries from March 12 to 15, countries in the Asia-Pacific region are most supportive of border closures – led by India (79%) and Vietnam (78%) ̶ which is not surprising, given where the disease was first encountered.

More than 3 in 4 people in the world’s other hot spot, Italy (76%), are also in agreement of this drastic measure followed by those in China (73%), and Russia (70%). …

Meanwhile, the countries that saw the biggest jump in this measure from a previous poll conducted on February 28-29 are all developed markets – the U.K. (+31 points), Australia (+29), and Canada (+28).

Don’t think for a moment that this will reduce dramatically after the peak of the pandemic comes to an end, either. As I wrote earlier, we have lived in a generation without epidemics or significantly close wars, for the most part, and the utopian allure of open borders were a luxury we could afford. Now that we understand the value of strong borders that can be closed when necessary, especially unilaterally, it will be at least another generation before we see people start drifting back to a serious embrace of open-borders philosophy.