We are now witnessing the casualties of new U.S. policies arriving at Canadian borders. More might soon follow as those who lack residence documents face a grim future and the possibility of deportation under the Trump administration.

This is the moment for Canada to extend the Canadian dream southward to young adults entangled in U.S. immigration and border control. A planned policy to welcome undocumented young people would easily fit Canadian immigration-policy goals.

They work and build families. Some were brought to the country when they were still in diapers by parents dreaming of a better life. Many only find out that they are not "legal" when they try to get a driver's licence. And although they are largely exempt from the latest immigration memos, U.S. President Donald Trump has offered no guarantees, and warned them "the law is rough."

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Despite English fluency and U.S. work experience, despite U.S. diplomas and even advanced university degrees, these young people face dismal career prospects. They are hesitant to make close friends for fear of revealing their undocumented status. They live in constant dread that they will be deported to their parents' homeland, countries many do not remember.

The U.S. public is sympathetic to their plight. Most Americans favour legalizing undocumented residents. Multiple attempts have been made to pass a DREAM (Development, Relief and Education for Alien Minors) Act that would open a road to citizenship. But Congress has repeatedly failed to pass the bill, leaving only the coinage of "dreamers" to refer to those it would have helped. There is no chance of new DREAM Act legislation in the near future.

As a stopgap measure, the administration of former president Barack Obama introduced the Deferred Action for Childhood Arrivals (DACA) program. Under DACA, undocumented young people received work authorization for two years and were shielded from deportation. The program was open to those who arrived in the United States before the age of 16, had no police record, were in high school, had graduated from high school, or had been honourably discharged from the U.S. military. To date, about 750,000 people have become "DACAmented."

These are precisely the people who Canada looks for in its immigration program. The economic advisory council to Prime Minister Justin Trudeau recommended Canada focus a growing immigration strategy on business talent and international students. The DACA kids are young, with a lifetime of economic contribution in front of them. They are fluent in English, went to U.S. schools, have North American work experience – often in companies that can be found on either side of the Canada-U.S. border – and some have university degrees. To get DACA status, they had to be screened for security threats and criminal background, making them a pre-vetted group.

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These young people hold incredible promise for Canada. They are exceptional people. It is not easy to go to college or university when you are undocumented. But within the flagship University of California public system, hundreds of dreamers are pursing higher education in degrees ranging from math to sociology.

In 2014, Sergio Garcia became the first undocumented lawyer certified to the California bar. That same year, Jirayut Latthivongskorn became the first undocumented medical student enrolled in the University of California, San Francisco. For each of these dramatic against-all-odds success stories, there are thousands of other ordinary immigrant kids who just want the security of citizenship, a good job and a stable home.

Unfortunately, their American dreams have never appeared more remote. Mr. Trump campaigned on an explicit "America First" message. Since taking office, he has advanced plans to build a wall on the U.S.-Mexico border and sought to temporarily halt refugee admissions. The White House has not yet made an explicit statement on the DACA program but, at best, the program will end. At worst, the government will use the information collected from those who applied to begin mass deportations.

Canada is already seeing the arrival of asylum seekers from the United States. If DACA is ended, a flood of new arrivals is possible. Canada cannot take all of these young people, but a targeted program of 10,000-30,000 would allow Canada to select the very best matches with Canadian society and the economy.

As immigrants to Canada, they could be a special addition to economic-stream migrants, or fall under a new program akin to that for international university students.

Offering a Canadian dream to DACA recipients might also be positive for foreign relations. Mr. Trump faces a problem in how to deal with the country's undocumented population. Deporting millions would be politically, logistically and socially impossible, but rendering their lives difficult is a distinct possibility.

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Canada has long benefited from the flow of people educated and raised in the United States, who left for a variety of reasons. Today, the United States is among the top-10 source countries of permanent residents. Looking further back, an estimated 40,000 draft dodgers fled conscription during the Vietnam War, representing what the Immigration Department called "the largest, best-educated group this country ever received." Dreamers could be a close second.

Irene Bloemraad is a professor of sociology at the University of California, Berkeley and senior fellow at the Canadian Institute for Advanced Research. Ratna Omidvar is an independent senator for Ontario.