Indeed Otto, with their many decades of publications, their websites, and their well attended meetings, the NHRHTA and the ELHS are certainly not secret organizations. If they are not know in the "intellectual community", I would suggest perhaps that community is not making enough effort to identify the resources that are available out there. In my experience some excellent railroad historical societies tend to be overlooked by big city historical groups, and it tends to be due to intellectual elitism rather than lack of communication.
"We Repair No Locomotive Before Its Time"