I had fun researching and reading about what I’ll call “History of Alternative Spirituality/Occult.
Here’s some thoughts on Spiritualism. The “Big-Daddy” of Modern Spiritualism would be, in my opinion, Andrew Jackson Davis. He wrote: The Principles of Nature (1847) and The Great Harmonia (1850). He died in January of 1910.
In 1875, we got Helena Petrovna Blavatsky and the founding of Theosophy (the Theosophical Society). This was less Spiritualistic and more Occult than Spiritualism. By 1885, Andrew Jackson Davis would have been married 3 times and had all of them end. His popularity very likely diminished after that. In 1888, Blavatsky would write The Secret Doctrine. A massive 2 vol. set that few would read completely. She had already written another 2 vol. set earlier called: Isis Unveiled (in 1877 ?).
Even though Davis’s popularity faded, many people were still interested in Spiritualism. Why rely on Davis? People wanted to communicate with the dead on their own. Then we got “the Ouija Board” (in 1891?)
But Science and Materialism were marching on, and we also had Robert G. Ingersoll “The Great Agnostic’ and his writings from about 1872 to 1899. In 1902, after Davis’s 3 marriages, Frank Podmore would write “Modern Spiritualism”. I believe this was a critque. Then, 1914-1918, we had World War 1.
By the 1920’s, there were all sorts of beliefs one could get into: Spiritualism, Theosophy, “The Mind-Cure Movement” (as William James called it), Psychology, Christianity, Mysticism and more. Spiritualsim would still be popular in England. Arthur Conan Doyle would turn to Spiritualism, and Arthur Finlay would write the book “On the Edge of the Etheric”. Then, in America, we would have the Great Depression and also World War 2 and alot of people were likely too busy for alot of reading.
That’s my opinion, from reading and researching. I wasn’t there but I think that’s close to how things went. If you want still more info, a good book on this kind of stuff is “Occult America” by Mitch Horowitz. Amazon.com should carry it.