Dawson City in Canada's Yukon Territory. I think the image on the postmark is a dancing girl: something you'd see in one of the towns saloons during the gold rush. Dawson City was at the center of the Klondike Gold Rush at the end of the 19th century and for a few years during the height of the gold rush the town's population swelled to 40,000. Hence the "city" designation. Today it's population is just over 1300 and actually has a "town" designation, but it's still called Dawson City.