https://techcrunch.com/2020/03/18/u-s-and-canada-border-to-close-to-all-but-non-essential-and-travel-says-trump/

The U.S./Canada border has remained open despite measures by both countries to block and limit international flights and mobility in light of the coronavirus pandemic, but that is changing today as the two countries have agreed, “by mutual consent,” to suspend any movement between the two beyond “essential traffic” and “trade,” as first revealed via President Donald Trump on Twitter.

Earlier this week, Canada announced during a press conference with Prime Minister Justin Trudeau that it would be closing its borders to all non-citizens and residents, with the exception of American citizens. He was asked multiple times during the Q&A session at that briefing about why the U.S. was exempted, given that the rate of new cases in the U.S. was now large and growing larger at a rapid pace.