I've been reading Ribsy to Mary, and it's so weird, reading it as an adult who knows where everything is located. Like, in the first chapter, they stop at the intersection of 82nd and Klickitat Street, in Northeast Portland, OR. That's where the Original Taco House is located. On the other side of the intersection is a mostly abandoned strip mall. The only things there besides empty buildings are a porn rental store, strip clubs, a marijuana shop, a gas station and McDonald's.
Pretty sure that wasn't the case when the book was written in the 60's.
They go to Clackamas Town Center, which is the big mall in the southeast area. Then Ribsy gets taken to the western edge of Portland, into the Beaverton/Hillsboro area. Again, the book was written in the 60's, so the western edge of Portland is only ten miles away from the starting point. Today, the western edge of the city goes much, much farther. When you're driving through the area, you can immediately tell when you've hit the city border, because the scenery instantly changes from cityscape to farmland. There are some heavy-duty laws in place to prevent the city from expanding any more in that direction.
After that, the book's geography gets a little vague, as Ribsy travels east. He visits an unnamed elementary school and the fictional Zachary Taylor High School. All the high schools are named after presidents in that school district, so really, it could be any of them. In the end, Ribsy arrives at an apartment complex, which could be pretty much anywhere. No mention is made of the giant river that bisects Portland.