[This has been updated 4/03/20 to clarify the restriction on land and ferry crossings, and to include the links to the full text of the agreement in the Federal Register. Air travel has not been restricted by these agreements.]
On March 20, the U.S. Department of Homeland Security announced that the United States, Canada and Mexico would close their borders to "non-essential" travel (land and ferry crossings) effective March 21. Each agreement would last a minimum of 30 days, subject to extension upon review. This does not apply to air travel.
“'Non-essential' travel includes travel that is considered tourism or recreational in nature."
Read U.S.-Canada announcement. Read full details in U.S.-Canada Federal Register Notice.
Read U.S.-Mexico announcement. Read full details in U.S.-Mexico Federal Register Notice.