40 Mile Trail Search

The bike trails around here keep commenting on this 40 mile loop around the peninsula, but we have yet to actually see a real loop on a map. Anyone know where it actually is? The Green Way maps don't exactly make it clear. This morning we did part of what we think is that trail. From our house we took Willamette to the trail head by Fred Meyer's. It goes along a drop-off that the train runs through for a mile or two. Then, after crossing a few major roads, it gets into wilderness areas (loosely applied in pdx), along a couple lakes, and then off to the tip's park. We didn't go all the way to the tip today but it would be a great little day trip, maybe 15-20 miles round trip.