The group published 50 thousand tracts annually in the middle of the war, but then that dropped dramatically afterwards. Volumes were down to about 14.5 million in the early '60s.
According to the publisher's house history, Where There is a Vision, the WWII years were the most prolific because of the tracts purchased and distributed to and by U.S. soldiers. It's also the case that after the war, some of the company's attention shifted from conversion literature to literature for the converted. Many of the tracts that were printed were also more expensive to print because they were in full-color, produced with the latest reproduction technology.
There was, additionally, a push overseas, notably into post-war Europe and Africa, where separate presses were established to print gospel tracts for those cultures.
There was a rebound of American tract publication in the '80s, with 26 million printed by Good News Publishers in '88. In the era of televangelism, there was a renewed interest in tracts, that old fashioned media of gospel distribution. The publisher reported in '88 that:
Literature evangelism, rather than being centered on a few media personalities who have no personal contact with their audience, involves thousands of individuals sharing the gospel in a personal way on a one-to-one basis. In addition, mass media broadcasts are much less permanent than printed literature. Once the broadcast is over, the message is lost in the airwaves rather than being something permanent that a person can read over and over again.Tract publication rates have, nonetheless, declined again in the 21st century. The group's website says they now publish 16 million annually. That's down 10 million since the late '80s, and less than a third of the tracts produced in '43.
There has been some serious debate among evangelicals in recent years about the value of gospel tracts. Some worry they're not effective means of communication or, worse, communicate the wrong things. Good News continues to print and distribute tracts, just not as many as it once did.