TORONTO -- An agreement has once again been reached between Canada and the United States to keep the border closed to all non-essential or "discretionary" travel for another month, Prime Minister Justin Trudeau has announced.

The extension on the existing agreement means that the border restrictions will stay in place until July 21, even as both countries continue to reopen their economies.

"This is an important decision that will keep people in both of our countries safe," Trudeau said Tuesday.

The agreement, as it stands, exempts the flow of trade and commerce, as well as temporary foreign workers and vital health-care workers such as nurses who live and work on opposite sides of the border. Tourists and cross-border visits remain prohibited.

Deputy Prime Minister Chrystia Freeland said the measures apply to "to all of Canada's borders."

"When it comes to the Canada-U.S. border, as the prime minister announced today, we have agreed with our American neighbours to roll over for another 30 days, the measures that we have currently in place," Freeland said on Tuesday during the federal ministers' update on COVID-19.

She added that the conversation to extend border restrictions was "very collaborative" between the two countries.

"It was based on a mutual recognition that the measures we currently have in place are working very well," Freeland said.

This is the third time the agreement has been extended, after first being imposed in March, with the current extension on border restrictions set to expire June 21.

The prime minister continues to emphasize that reopening Canada’s border to international travel would be risky as countries worldwide are still working to contain outbreaks and more robust contact tracing has yet to be established.

To date there have been more than 99,000 COVID-19 cases in Canada, and more than 8,000 people have died, while the U.S. currently has more than 2.1 million COVID-19 cases and more than 118,000 people have died in that country. Newly reopened states have started to see increases in their active caseloads and hospitalization rates in recent days, escalating fears of a second wave of infections in the U.S.

With the border closure still in effect and few available flights, the Canada Border Services Agency (CBSA) says there continues to be a significant drop in travellers arriving in Canada from the same time the year before, despite recent reports of some American tourists visiting Banff.

"In terms of the situation which has been reported on in Banff, we are very clear that Canada's rules are: you can enter for essential reasons, but not for non-essential ones," Freeland said.

Freeland said the RCMP in Banff are following up on the situation and encouraging Canadians to make them aware if they see other Americans who fall into the non-essential travel category. She added that the CBSA will also be watching more closely for travellers who may be entering for non-essential reasons.

"Minister Blair has instructed the CBSA to take further care to ensure that the people coming into Canada from the U.S. are truly coming for essential reasons. And let me just add, these measures are in place for a reason. They are to protect us, and they are to protect our neighbours," Freeland said.

While the urge to travel may be growing after months of staying home, Freeland cautioned foreign travellers to stay away for their own health and the health of Canadians.

"I would say to our American friends and neighbours: I love the Rockies too. I grew up in Alberta. Personally, I can think of no better place to spend time. But now is not the time to visit," Freeland said. "Hopefully we will be back to normal at some point soon."

Canadian health officials will continue to watch the trajectory of the United States' epidemic to see whether it will be appropriate come July 21 to lift restrictions or continue to maintain them.

"As we have heard from our doctors, although we are succeeding in flattening the curve in Canada because of the hard work of every single Canadian, we're not there yet. And it's important to continue to be cautious and prudent," Freeland said.

REUNITING CROSS-BORDER FAMILIES

Cross-border families will still be able to reunite under certain stipulations despite the extension of the closure of the Canada-U.S. border.

As of June 9, immediate family members of citizens or permanent residents who are foreign nationals can enter Canada to be reunited, under a new limited exemption to the current border restrictions.

The policy will allow immediate family members from the U.S., as well as from other countries, to be able to enter Canada under a series of stipulations.

"The purpose of this measure is not to allow people to come and go into Canada whenever they like, but rather to help Canadian families reunite during this unprecedented time," Minister of Immigration, Refugees and Citizenship Marco Mendicino said when the policy was announced last week.

Eligible immediate family members will be spouses, common-law partners, dependent children and their children, parents, and legal guardians. In order to be allowed in, the family members must have a plan to stay in Canada for at least 15 days, and they will have to self-quarantine for 14 days as soon as they enter the country.

The family members in Canada who will be welcoming their loved one will have to confirm they have a suitable place for their family to self-isolate for the first 14 days of their stay, where they will be able to access food and medication. Their place of quarantine cannot be where they would have contact with a vulnerable person, such as a senior or someone with pre-existing medical conditions, unless that person consents.

It will be possible for foreign nationals with immediate family in Canada to come for 14 days or less, but they need to prove that their reason for travel is not discretionary and that they can comply with the quarantine.

Some examples of reasons for travel that are considered essential, according to the government, include work and study, critical infrastructure support, economic services and supply chains, shopping for essential goods, and for health concerns, immediate medical care, or safety and security reasons.

The Immigration, Refugees and Citizenship Canada (IRCC) website states that optional or discretionary reasons for travel include tourism, recreation, or entertainment.

The ultimate decision, however, is up to individual CBSA officers who have the final say on whether a traveller's reason for crossing the border should be permitted.

NOT KNOWN WHEN BORDER WILL REOPEN

Despite mounting pressure from business interests and border communities that depend on a steady flow of traffic between the two countries, Trudeau did not provide any details Tuesday on how border restrictions will be eased when the time comes.

However, the extension does give Canadians officials more time to decide what further measures will be required when the border does reopen to ensure that people crossing the border don’t become vectors for further spread of the deadly respiratory virus in Canada.

When asked what the benchmarks will be for signs it's an appropriate time to loosen restrictions after the border closure was extended for the second time, Chief Public Health Officer Dr. Theresa Tam said in May the first step would be carefully reopening travel restrictions within Canada.

She said drastically limiting who has been able to enter the country over the last few months -- specifically international visitors -- has been key to Canada controlling the outbreak.

Even when international travel can resume, Tam said the 14-day mandatory quarantine and follow-up enforcement of that order will remain "a cornerstone" of the disease control measures.

"Fundamentally, it's about ensuring that whatever we do, the system is still able to detect and still able to cope with any introduction," Tam said.

With files from CTVNews.ca's Rachel Aiello