Hello, all! While working on routing for the OST, I found that the old headquarters was located inside the Gunter Hotel here in San Antonio. The hotel still exists, and so does the collection from the Trail association!
It was apparently donated to St. Mary's University, and I'm planning on seeing the whole group myself in the coming days.
The collection website: http://library.stmarytx.edu/ost/
Great. Please post some photos. You do know about the OST100 association (http://www.oldspanishtrailcentennial.com/), correct?
Sure do! I'll get some pics up as soon as I can visit!