Six years ago there was no PRRT&HS chapter in Chicago.  A couple of us decided we should find out the interest and posted an invitation on one of the blogs regarding the PRR.  We now have nearly 100 people in Chicago who do have interest and regularly have more attendees at our chapter meetings than most of the older chapters.  We have even been asked to host the national convention here is the Chicago area  in 2009.  The amount of information I have personally learned has been staggering and the wealth of knowledge is phenemonal.  So if you have interest in a particular road find a way to see if there are others in your area and what can be done to get together for discussion and or forming a chapter of that roads historical society.  It is well worth the time.