Days Gone contains 20 Radio Free Oregon Collectibles. Rather than having locations in the open world they are radio calls that are tied to story progress. They are all automatic story-related collectibles and cannot be missed. The last one becomes available after finishing the Epilogue. Simply finish the Story and you'll get all of them automatically, no work required.

Every couple story missions you will get a new radio call. You can skip these by holding the Touchpad and they will still get added to the Collectible Menu.

When the calls stop coming in you must advance the story further. There are two Points of No Return during the story that temporarily lock you out of earlier regions but this doesn't affect the radio calls, they will keep coming in regardless. Nothing is missable.

Do note that the numbering from the in-game collectible menu is way off for this. The calls trigger in a completely different order than the in-game collectible menu has them listed. Just know this is absolutely normal.

Here's a list of all Radio Free Oregon Calls (same order and numbering as in collectible menu):

1. Nero Death Camps
2. It's All a Lie
3. My Cold, Dead Hands
4. Numb the People
5. Home of the Free
6. The Dead Can't Speak
7. The Just Shall Not Starve
8. Bunker Down
9. Animals Don't Watch the Sky
10. Global Conspiracy
11. The Federal Ark
12. The Black Helicopters
13. They're Coming For Us
14. The Advanced Guard
15. Built to Last
16. Traitors Shall Hang
17. Cleanse Our Minds
18. The Earth is Ours
19. Property Rights
20. We Are Watching

That's all 20 Radio Free Oregon Collectibles in Days Gone, one of the easiest collectibles ever.