Canada has lifted its prohibition on Americans crossing the border to shop, vacation or visit, but the United States is keeping similar restrictions in place for Canadians.
The reopening Monday is part of a bumpy return to normalcy from COVID-19 travel bans.
The border has been closed to nonessential travel since March 2020 to try to slow the spread of the coronavirus.
Travelers into Canada must provide proof of vaccination for either the Pfizer, Moderna, AstraZeneca or Johnson & Johnson vaccines and provide a negative COVID-19 test result taken within 72 hours of their arrival.
Unvaccinated children younger than 12 can enter the country with their fully vaccinated parent or guardian. However, those children are asked to avoid "group settings," like camps or day care, for 14 days upon their arrival.
The government is also asking travelers to be ready with a plan in the event they test positive for the virus during their visit and have to quarantine.
While Canada has opened its borders, the U.S. is keeping its side closed to non-essential travel until at least Aug. 21. The decision to keep its border closed to travelers and tourists from both Canada and Mexico represents a stark divergence in return to normalcy at North America's busiest border crossings.
The re-opening of Canada's borders also comes a day after unions representing the country's border agents ended strike actions that could have caused major delays at crossings. The agents took "work-to-rule" action last week after saying they had been working without contracts for several years.