I've been digging through some of the oldest maps available for our area - those produced starting in the early 1850's by the Surveyor General of the United States, originally to help implement one of the donation land claim acts.
They are available at http://www.blm.gov/or/landrecords/survey/ySrvy1.php , as stated on the Portland Hikers site recently.
The best of these include old trails, including some marked "Indian Trail" and other early information. However, its obvious that the early maps, which cover land most likely to be homesteaded, are the best, while those in the Cascades were done later and to a lower standard. Still, some areas with a good surveyor had very useful information about early trails, which may lead to some fruitful searching - or not as some of these may have been abandoned well over 100 years ago.
For instance, Squaw Meadows has the notation "Campground of the Warm Springs Indians while picking berries". One of the nearby trails is described as "Trail from the Willamette Valley to the Warms Springs Reservation". This is on Map t040s060e_002, which includes much of the Roaring River.
And there are mining claims reported. Of great interest to me are the two claims above Pansy Lake. The report states there are not one but three shafts there, and it locates them all. The one we know about on the abandoned trail is the largest, and the report states it is much bigger than it is.The claim map also shows a cabin just south from the lake, which I suspect was at the larger flattish camp site near the outlet.
The problem is that some of the most interesting areas were never mapped, such as much of the Olallie area and others in the highest and most remote parts of the Cascades, and other areas while mapped contained no information about trails. But for the areas that were well done, this is the oldest trail information I know of.
Maps of the urbanized Portland area were from the 1850's, when so little settlement had occurred that plowed fields were drawn in as they were unusual landmarks. What would late become Gladstone had at High Rocks an "Indian Village" still present. A little ways downstream were "Indian Graves", soon to be desecrated and destroyed. They were likely canoes mounted on posts. The same map has across the Clackamas from the above "Clackamas City", which washed away in 1861 along with Linn, Canema and Charbonneau. Linn was move west uphill and is now called West Linn. Canema also moved uphill and is now a small neighborhood within Oregon City. Charbonneau was lost is now an archeological site in a state park.
These maps are bigger than the 1 mb limit. They are slow to download from the BLM site.
While looking for the BLM site I discovered a USGS one instead. It contains older USGS, some close to 100 years old.These are PDFs in color, and though I haven't had time to check them out, they should have some useful trail information. I have found one map date 1916; I just tried Breitenbush and Bagby and they only went back to the 1980's, so it will be hit or miss. Most seem to be 1960's or later.