The strict border rules are meant to stop the spread of new variants.
The border has remained open for essential travel only through the pandemic.
New arrivals will be forced into a mandatory three-day hotel quarantine at their own expense.
“We’re always open to strengthening them as necessary,” Trudeau said, referring to measures restricting international flights.
Many Canadians own property in Point Roberts, Wash.
The vast majority of people crossing the border were deemed "essential" travellers and did not have to quarantine.
Those who don’t directly qualify under the expanded family rules will be able to apply to enter for compassionate reasons.
The RCMP apprehended 21 people in May and six in April.
The border has been closed to all but essential traffic, goods since mid-March due to the COVID-19 pandemic.
Canada, U.S. are both "very comfortable" with mutual ban on non-essential travel.