I can help a little bit with some of the WA drive-ins.
For starters, the town isn't 'Bothwell'--it's Bothell. And yes, that drive-in was in Kenmore, but at that time Kenmore was just a neighborhood, and considered part of Bothell. I suspect all mail for Kenmore went through the Bothell post office at that time.
Centralia--it is or was called 'Twin City Drive-In' because Centralia and Chehalis are close enough that their city limits abut, thus they're one of many pairs using 'Twin Cities' as self-descriptive.
(Twin Towns is more like it)
Everett
The Puget Park Drive-in's location is most easily given as 'just south of the intersection of I-5 and 128th St. SE'. If you go to Google Maps and zoom down to that intersection, then go to satellite, you get a nice pic of the place.
I don't know anything about the one in Beverly Park--it was long gone before I spent any time in the area. Same for the one(s) by the Snohomish River.
Kent
According to http://driveintheater.com/list/washingt.htm the El Rancho--which is indeed in Kent; SE Kent, if you will--is dead. It shows up nicely on the most recent satellite pic on Google Maps; maybe I'll drive over there this weekend.
The Midway, sadly, is almost completely gone now. Was a big site for swapmeets for a long time.
Seattle
I can give you the intersection to look at for where the Aurora Drive-In used to be, but there are no signs of it any more.
135th and Aurora Ave N.--the drive-in used to be where the big warehouse store is now, just NE of that intersection.
The Duwamish I never went to, and didn't spend time in that part of town, so no help there.
Oh, and in Oregon--the drive-in just north of Milton-Freewater was, I think, named the Starlite. I used to ride my bicycle over there when I was 11 to 15 years old. That'd be the 2nd half of the '50s.
-denny-
