Re: What was Ginsburg & Klausner, S Fallsburg, NY (Catskills) not listed as hotel #usa
At the end of the nineteenth century and very early twentieth century, there was an effort to settle Jewish farmers in various places, including the Catskills. As supplements to their income, they opened their homes as boarding houses. That became the germ for the later start of the Borscht Belt. Here is a link describing this early time in South Fallsburg. https://thebaronhirschcommunity.org/the-catskills-farming-the-jewish-alps/#more-2661
There is a book, “Jewish Farmers of the Catskills” by Abraham Lavender and Clarence B Steinberg, for further reading.
There were already trains running back and forth to NYC from this area during this time, so the population was not static, rather fluid going back and forth to Lower East Side, Brooklyn, etc.