I just returned from a vacation in Montana. Lots of fires and smoke there as there is here in Washington. If Cooper landed in the Columbia River, he almost certainly died and that is a d cent possibility! After over 45 years if that is the case, I feel it highly unlikely that we will find any more real evidence. I guess that's why I am exploring other scenarios. Since his flight originated in Portland, its possible that his escape vehicle might have been somewhere in Portland vicinity. Since there are only 2 bridges that cross the Columbia being the Interstate 5 and the Railroad bridge, I decided that the railroad bridge would be by far the most likely escape path. Why ? Most importantly is the fact that you would be more visible on Interstate 5 but also it's a draw bridge and always manned 24/7 by a bridge crew.
If Cooper died in the heavy woods around Ariel, how could the Money find its way to Tina Bar ? I'm pretty sure he's not out there ! So I think IF he survived the jump, he could easily walk his way to the railroad bridge and cross into Portland. There is and has been a railway from Yacolt that travels through Battleground, Brush Prairie and connect to main line a few miles from Vancouver/Portland railroad bridge. I have checked out the full line and it's all still usuable and easy walking. I took the Amtrak round trip from Longview to Portland to try to ascertain what it would be like if you were to walk it. The only dangerous part would be IF a train would come along as you were crossing 2 rather long bridges. It's a double track BUT Cooper would be very visible to the train engineers ! There is room to duck out of sight but not for the faint of heart. Of course jumping out of a plane in darkness isn't for the faint of heart either. After noting there are Hobo camps under the bridges, my train ride showed me NO sight of any Hobo camps as they are far below the track level. So it would be entirely possible for Cooper to never encounter any hobos ! From being VERY familiar with the areas on the Oregon side of those tracks in 1971, I have a lot of places where I know Cooper could have easily left a escape vehicle which would be undetected by anyone. He would have to be a total idiot to leave his vehicle at PORTLAND airport ! I don't think he was an idiot !