A map of the courses around Portland, you say? Gosh, what an idea...
But I don't think we can be too picky. In the urban core, there's very little land available.
That said, SE Portland and northwestern Clackamas County (including Oregon City and Lake Oswego) is the biggest "hole" in the map
, if you look at where people actually live. The area in between Lunchtime, Rockwood, Champoeg, and McIver is a big chunk of land that's home to hundreds of thousands of people and zero disc golf courses. If Harmony goes in, the biggest gaps will be NE Portland and Tualatin.
(Interestingly, the geographic center of the current DG-free zone is just northwest of Gladstone, and very close to Meldrum Bar Park. Bob Cabal has wondered about -- and wandered about -- Meldrum Bar in the past, but no one seems to know who owns it!)