Re: Question about ISFDB statistic

Charles Packer wrote:

Why the wide swing in the number of titles in the ISFDB
by year of publication -- 50% jump -- from 1938 to 1939?
It's hard to believe that it reflects a step function in public
interest. The context is as follows:
 year 1936 count 4738
1937  4628
1938  4117
1939  6245
1940  6685
1941  5746
1942  5513
 

There was a bit of a boom in SF magazines about this time.  Unknown, for example, was launched in 1939 as were Startling Stories and Planet Stories.  I presume there were others I don't know about.
Secondary publication and reprints became more popular, as I mentioned elsewhere.
Pohl's two magazines at this time were launched in 1940, too late to account for the step function, but part of the 39-41 boom which came to an end due to wartime paper shortages.
William Hyde