I am reading "Rio Grande Glory Days" by Gilbert Lathrop, and the author biography on the back says that Mr. Lathrop wrote under multiple pen names, including "Helen Wissmath". I Googled Helen Wissmath and found nothing related.

How often did male authors write with female pen names? Does anyone know of any work by Lathrop under the Wissmath pen name?

I found the answer - there is a bibliography for Lathrop at the back of the book.

It appears this is not really a pen name. It must be that Lathrop wrote the stories of a real Helen Wissmath from interviews.

I'm glad you're reading "Snap" Lathrop there!! He, Harry "Haywire Mac" McClintock, William F. Knapke, and others had wonderful tales to tell about working on railroads in the "goodle days," some of which weren't so good--at least at the time. (Later they could laugh about some of those escapades, and we can too, because we aren't the ones going through them!)

I don't know if you've reached it yet, but the best story out of "Rio Grande Glory Days" involves a rear end brakeman and his cooking ability--or more properly, the lack of it!!

I mentioned Haywire Mac. He would later have a recording career as writer and singer of some interesting "country" style songs, among them "Halleluiah, I'm a Bum," and "Big Rock Candy Mountain," a hobo's idea of Heaven. If you've ever seen the film, "O Brother, Where Art Thou?," Haywire Mac is in the soundtrack of the opening sequence with his 1947 recording of "Big Rock Candy Mountain."

Haywire Mac is also prominently featured in William Knapke's "The Railroad Caboose." That was Knapke's attempt to tell the history of cabooses up to about 1969. The book was published when Knapke was 99 years old!! He mentions this age when he says in the book about something, about "if I live to be 100, and it looks like I might do that."

I seem to recall he did make it to the century mark, and the book's good reading, too.

Female pen names for male writers are not that unusual. I am a male who is a moderately successful author of romantic novels. I have two different nom de plumes for my writing endeavors. There is a bias in that part of the publishing industry against male authors, grounded in the belief that men are not as sensitive in affairs of the heart.
And of course, look at how many here are under pseudonyms. (Myself included)