Doesn't the US have out-of-hours pharmacies, or out of hours doctors, or urgent but not emergency treatment centres?

Not really. There are non-ER/non-hospital urgent-care centers, but they usually keep to roughly normal business hours. For after-hours care, the ER at a hospital is often your only option.

Depends on where you are. Some places have 24-hour Urgent Care centers that can handle the basic stuff that doesn't need a real ER.

But many places don't have any kind of Urgent Care centers, much less one that is open 24 hours a day.

Yes, that's why I said "usually" and "often".

For those from tri-state area: folks, PM Pediatrics is a blessing. They're open till midnight, waiting times are reasonable and they are billed as PCP by the insurance.

Yep. Usually the rule of thumb is:

* Potentially life-threatening emergency: ER

* Something like a broken bone or fever that needs to be fixed asap, but not life-threatening: Urgent Care

* Everything else that can wait a bit: regular doctor appt

Yes, kind of. They can handle a few things (ear aches, something that requires anti biotics, basic pain relief) with a nurse practitioner.

Not really. I live in Queens, NYC and there's no 24 hour urgent cares I'm aware of within a 30 minute drive.