Corbeil said there are about 50 people in Porthill, but 16,000 just over the border. "A lot of Canadians, especially around British Columbia, have relatives around the world and for them to get their Christmas packages to them, if they mail them in Canada, they're not going anywhere," she told the Stamp Collecting Forum.

Even when Canada Post is operating, Corbeil gets a lot of Canadian business. "This is a small town," she said. "If you really worked at it, you could find 50 people in the area. I have 700 post office boxes, and 660 are Canadian."

Corbeil says her Canadian customers prefer the US Postal Service. "It's a neat place to work, because you don't get any hassles or anything. People are not unhappy, because Canada is so much slower. So they really appreciate the service of coming down here and being able to mail a letter and have it there in a reasonable amount of time."

And the US mail system is much faster. "What takes two or three or maybe four days in the States to get one place," she told the Virtual Stamp Club, "takes 11 days to 2 weeks to 3 weeks in Canada."

The Associated Press reports other border post offices were busier, too, such as Oroville, Washington, about 6 miles from the border. AP also reported some Canadians were crossing the border to mail packages back into Canada. While that wouldn't work for Parcel Post and Priority Mail, it did for Express Mail, which uses a private carrier in Canada for its deliveries.