In the present day, American professors (at least most of them, I think) get their jobs after obtaining Ph.D.s. I've been trying to do some research for a writing project that's set circa 1900, and it seems like the requirements at that time were much more fluid—in some sources I find, there are few professors at a given college that have anything higher than a Master's degree. My main questions: Have the requirements for becoming a professor become more strict/streamlined since then? Did degrees work differently? What was the path to professorship around that time? Was it considered a respectable job like the law or was it on the same level as other educators? How did tenure function? Were professors, like now, expected to conduct research and publish in order to obtain job security?
Any information, even tangential, is much appreciated.
Circa 1900, the only thing someone really needed to become a college professor was a Mr. on his calling card.
And I'm only being slightly tongue-in-cheek. At that time, colleges and universities were typically staffed by men who were considered smart. Which isn't to say they weren't, but "smart" was the main attribute that lead to them being hired. The reason they were able to get an appointment with the president or dean of the college or university was because they were, typically, a smart man with social connections. In other words, colleges and universities hired men to teach that they felt would fit in with the culture and climate at the school (the phrase a "Harvard man" applied to more than just the students) and had a solid understanding of the content they needed to teach. This understanding didn't necessarily translate to pedagogy - learning sciences and psychometrics were only just beginning to take shape.
There were, of course, exceptions. 1900 is right in the middle of a massive sea change around the purpose of higher education. In this comment, u/indyobserver gets into land grant colleges and HBCUs and here, I get into some of the history around early women professors.