As Canadians scramble to get passports to meet new U.S. travel regulations, a large number of residents are discovering that they aren't Canadian citizens.

Some, known as "border babies," were born in a U.S. hospital because it was closer than the hospital in their Canadian homeland.

Others were victims of a little-known law that applied between 1947 and 1977, which stated that if you lived outside Canada on your 24th birthday and failed to sign the right form, you automatically lost your citizenship. These people are being told that their chance to remain a citizen expired years ago.

One border baby, Mallo Clark, his two brothers and a sister were all born in Westhope, N.D., because they live in Lyleton, Man., right near the U.S. border.

The Clark family has been living within 10 miles of their current homestead since 1899, and in Ontario for years before that.

They went to school in Lyleton. Their parents got child tax benefits for them. When they were old enough, they voted in elections and paid taxes.

Mallo didn't find out he had a problem with his citizenship until he was planning a trip to Mexico.

Worried about collecting pension

"I went to get a passport, and no such luck because I have a U.S. birth certificate. You can't get a Canadian passport on a U.S. birth certificate. I can get a U.S. passport, but don't want one, thank you."

His brother, Claire, did get a U.S. passport a few years ago because he needed documentation to travel. Now, he's worried he won't get his Canadian citizenship in time to collect his Old Age Security from the government.

"I've paid into it from the start, and if I don't get my money out — we worked for it, paid for it, entitled to it. Just a little piece of paper that's stopping me," Claire said.

You have to be a citizen or a landed immigrant to get the Old Age Security, and the Clark siblings are neither right now because their parents didn't fill out the right paperwork when they brought them back to Canada after their birth.

British Columbia resident Barbara Porteous is a victim of the "24th birthday" law. She applied for a passport last year and was told in a letter from Citizenship and Immigration that she would have to apply to become a landed immigrant after spending most of her 70 years in Canada.

"These documents confirm you were a Canadian citizen, but you ceased being a Canadian citizen on June 14, 1960, the day following your 24th birthday," the letter read.

Worked as a returning officer

A Canadian, born in the U.S. to a Canadian father, Porteous has lived in Osoyoos, B.C., for the last 46 years, and even worked as a returning officer for Elections Canada.

According to Canadian census data, there are an estimated 10,000 to 20,000 people in Canada who could find out they've lost their citizenship when they apply for a passport.

Citizenship and Immigration Minister Diane Finley has acknowledged the provisions are unfair and said the government would shift its policy to fast-track the process of becoming a citizen for these people.

Prior to this week, Canadians without status would have to apply to become landed immigrants — a process that takes three years or more.

Now, they will be able to apply for a grant of citizenship in just eight months.

"We're trying to right the wrongs of the past and do the reasonable thing, the right thing, for what are essentially Canadians in all but name," Finley told CBC News in an exclusive interview.