Gunpowder was at a premium during the War of 1812, and none was available when residents of this small border city wanted to add a traditional bang to their Fourth of July celebration.
No problem. They simply borrowed some from their neighbors across the St. Croix River in St. Stephen, New Brunswick.
So what if Canada and its mother country, Great Britain, were at war with the United States at the time? That was hardly sufficient cause for St. Stephen to refuse its neighbor.
"It's always been that way," says Bill Francis, who lives in his native St. Stephen but operates a gift and wood-products shop on the U.S. side. "There's a strong national identity, but people try to make it a community."
"I facetiously comment that we get along better than we would if we were in the same country," says Calais City Manager Nancy Orr.
St. Stephen Mayor Billy MacCready contends that the strong and enduring relationship is unequaled in any other pair of border-straddling communities along the 3,000-mile frontier.
Calais, a commercial center of 4,200 near the eastern corner of Maine, obtains its water from St. Stephen, a chocolate-making town of roughly 5,000. When a fire breaks out in either community, firefighters from both sides of the border routinely cooperate.
"The trucks don't stop at Customs when they're responding to a fire," Orr said.
Canadian golfers frequently travel to Calais to tee off, although St. Stephen recently opened its own course. Mainers frequently play hockey at an arena in St. Stephen, and swimmers in New Brunswick look forward to a new pool planned in Calais.
During the first week in August, the towns jointly sponsor an International Festival, which includes a parade that begins on one side of the border and ends on the other, reversing direction from year to year.
A significant number of people work in one country and live in the other. Some hold dual citizenship, and cross-border marriages are common.
"I probably dated more girls from St. Stephen than I did from Calais," said Calais Mayor Drew Case, whose wife is from St. Stephen. "Why? I don't know. It just worked out that way."
"Half the people around here have relatives who were born in Canada, or vice versa," said Barry Thompson, a U.S. Customs officer.
St. Stephen has no radio station, so WQDY-AM and FM in Calais serves both communities, broadcasting news and public service announcements from both sides of the border and carrying high school basketball games involving the Calais Blue Devils or the St. Stephen Spartans.
"International Radio, WQDY, 1 o'clock Eastern, 2 o'clock Atlantic time," the announcer says for the adjoining time zones, then gives the temperature in Fahrenheit and in Celsius for his metric neighbors.
General Manager Dan Hollingdale estimates that at least half the station's listeners and nearly half the advertising revenue come from the Canadian side.
Hollingdale holds dual citizenship, because he was born at Charlotte County Hospital in St. Stephen before Calais Regional Hospital opened in the mid-1950s.
The Calais-St. Stephen crossing is on a principal land route from New England to the Canadian Maritime Provinces and is one of the half a dozen busiest customs stops along the entire U.S.-Canada border.
Local shoppers often cross the border in search of lower prices and more plentiful selections. Residents say they are often recognized and waved through the border checkpoint when crossing to jobs or shopping.