A feud between two U.S. cities over who owns the trademark "Ice Box of the Nation" is heating up.

Fraser, Colorado Town Manager Jeff Durbin said the Minnesota town of International Falls has replied to a lawsuit filed by Fraser with a countersuit.

Fraser officials say their town has used the phrase since 1956, and officials in International Falls say they have used it since 1948. The dueling lawsuits ask city officials to prove it.

The two chilly municipalities fought an earlier cold war over the motto decades ago that ended in 1986 with Fraser giving up its "official" claim to the trademark in exchange for $2,000 from International Falls.

But the Minnesota city last year acknowledged it had inadvertently failed to renew its federal trademark back in 1996, even while keeping a state trademark up to date. That allowed Fraser to file its own application.

To outsiders it might seem ridiculous, but Durbin said it is important to Fraser's residents.

"We ought to get something out of it after having to live through winters here," resident Joan Christensen said.

The Summit Daily News in Frisco, Colorado, reported an attempt to settle it with a duel failed when Fraser wanted it to be a contest on snowshoes and the Minnesota mayor wanted a snowball fight.

On Sunday afternoon, the National Weather Service said, Fraser was the warmer of the two cities at a balmy 19 degrees. International Falls was 17 degrees.