The West is best as it's the best way to excuse the abundance of fire-arms and ammunition. I won't rule travelling to Canada/Mexico out of the question, but doing zombie apocalypses in Europe/Middle East/Asia is a mistake. Perhaps Russia would be a decent place, but it has a very homogeneous culture and that doesn't give room for the melting pot of cultures, ethnicity and ideology as America does.
I don't know why we would try to go back to the TLOU/28DaysLater/QZRP mentality of creating safe-spaces with military guard whitelists, it's just a bad idea and ends up not working. People don't WANT to sit in a safezone, even if it is safe. They'd rather play HL2RP. You cannot force these things to happen or else the player-base your targeting will reject them because everyone generally wants to be out in the boonies, fighting for their own bite and rather than forcing the opposite of that, we should embrace it and make it not such a grind to find a weapon/ammo, and instead allow people to get back into the action sooner than later.
Military should create the initial chain of events to help the citizens escape, then it should be left up to story progression throughout each of the following maps and allow player agency to determine where to travel next.
Think L4D2 but with roleplay and a mix of fast and slow zombies.