SIOUX FALLS, S.D. (AP) — Millions more Americans might qualify for dual Canadian citizenship under a recent change to Canada's requirements that has led to a surge in applications from its southern neighbor.

For people like Zack Loud of Farmington, Minnesota, it was a surprise to learn that under a new law, Canada already considered him and his siblings citizens because their grandmother is Canadian.

"My wife and I were already talking about potentially looking at jobs outside the country, but citizenship pushed Canada way up on our list," he said.

Since the new law took effect Dec. 15, immigration lawyers in the United States and Canada say they have been overwhelmed by clients seeking help submitting proof of citizenship applications. Driven by politics, family heritage, job opportunities and other factors, thousands of Americans are exploring whether the easier process makes now the right time to gain dual citizenship.

Nicholas Berning, an immigration attorney at Boundary Bay Law in Bellingham, Washington, said his practice is "pretty much flooded with this."

"We've kind of shifted a lot of other work away in order to push these cases through," he said.

Immigration attorney Amandeep Hayer said his Vancouver, British Columbia-area practice went from about 200 citizenship cases a year to more than 20 consultations per day.

How the new law works

Canada has been changing its citizenship laws for decades, whether to update historic interpretations of law or to address discrimination issues.

Previously, Canadian citizenship by descent could only be passed down to one generation, from a parent to a child. But the new law opened up citizenship to anyone born before that date who could prove they have a direct Canadian ancestor — a grandparent, great-grandparent or even more distant ancestor.

Those born on or after Dec. 15 need to show that their Canadian parent lived in Canada for 1,095 days.

Under the new law, descendants of Canadians are already considered citizens but must provide proof to obtain a certificate of citizenship. Hayer estimated that there are millions of Americans who are Canadian descendants.

"You are Canadian, and you're considered to be one your whole life," said Hayer, who advocated for the new law in parliament. "That's really what you're applying for, the recognition of a right you already have vested."

"The best way I can put it is like, if a baby's born tomorrow in Canada, the baby's Canadian even though they don't have the birth certificate," he said.

Americans interested in dual citizenship

American applicants have different motivations, but many say President Donald Trump's immigration crackdown and other topics have led them to seek dual citizenship.

Michelle Cunha, of Bedford, Massachusetts, said she decided to move to Canada after reflecting on decades of political activism and deciding she had "nothing left to give."

"I put in my best effort for 30 years. I have done everything that I possibly can to make the United States what it promises the world to be, a place of freedom, a place of equality," Cunha said. "But clearly we're not there and we're not going to get there anytime soon."

Troy Hicks, who had a great-grandfather born in Canada, said he was spurred by an international trip.

"I recently went to Australia and you know, first words out of the first person I talked to in Australia was basically an expletive about Trump and the U.S.," said Hicks, of Pahrump, Nevada. "It was just like, whoa, I walked off a 20-hour flight and literally the first words of somebody's mouth to me were that. ... So the idea of doing that with a Canadian passport just seemed easier, better, more palatable."

Maureen Sullivan, of Naples, Florida, said she was motivated by the immigration crackdown in Minnesota, which hit home when her teenage nephew encountered federal officers near his high school in St. Paul. Sullivan, whose grandmother was Canadian, said she sees citizenship in Canada as an option in case things in the U.S. "really go south."

"When I first heard about the bill, I couldn't believe it. It was like this little gift that fell in my lap," Sullivan said. "There was kind of this collective excitement amongst the (family) who just felt like, we wanted to feel like we were doing something to take care of our security in the future if needed."

How much will Canadian citizenship cost?

For those with documentation ready at hand, the proof of citizenship application fee is a relatively inexpensive 75 Canadian dollars ($55).

But costs will climb for those seeking help from an attorney or genealogist to locate records like birth, death and marriage certificates that can establish the lineage to a Canadian ancestor.

Cunha said she used an attorney and estimates the cost will be about $6,500.

However, Mary Mangan, of Somerville, Massachusetts, filed her application in January using advice from online forums.

"There are some situations where a lawyer might be the right thing, but for many people, I would guess 90% of people can probably do this on their own," Mangan said.

The website for the Immigration, Refugees and Citizenship Canada office, which processes applications, says processing times for a certificate is around 10 months, with more 56,000 people awaiting a decision.

The agency said that from Dec. 15 to Jan. 31, it confirmed citizenship by descent for 1,480 people, though not all were Americans. Last year, 24,500 Americans gained dual U.S.-Canada citizenship.

What's the reaction in Canada?

Fen Hampson, professor of international affairs at Carleton University in Ottawa, said Canadians are generally a "welcoming people."

Hampson said some also worry a surge of interest from Americans could delay efforts by refugees and asylum-seekers fleeing vulnerable situations.

"I think where people start looking askance is someone who's never been to Canada, who has very thin ties. They can get a passport, becoming Canadians of convenience. People don't like that," he said.