The War Exchange Conservation Act was designed to preserve Canada's balance of trade with the United States and banned the import of a broad range of nonessential items from the U.S., including such luxury items and diversions as cocoa paste, champagne and pictoral postcards. It also targeted what had become for many people not a luxury, but an essential distraction from the harsh realities of everyday life: the pulps.
Detectives. Sex. Westerns. Confession stories. These were topics that sold magazines, and Canadian publishers knew it. People would still want their weekly fix of grisly murder, winking pin-up girls, thundering hooves and vicarious heartbreak; if the Americans could no longer supply it, someone else would have to.
Canadian Pulp Fiction, 1940-1952 is a great site, full of information and nice design too.