USPS “Arrived at USPS Regional Facility”: what it means
“Arrived at USPS Regional Facility” means the package reached one of the large USPS sorting centers that serve a whole region. It's sorted there and sent toward your local post office.
Is it close?
It depends which regional facility it is. If the city in the scan is near you, delivery is usually one to two days away. If it's in another state, the package may pass through one or two more regional facilities first.
What comes next
“Departed USPS Regional Facility” when it leaves on a truck, then “Arrived at Post Office” or “Out for delivery”. A package can sit at a busy regional center for a day or two before its departure scan.
When to do something
If it's been at the same facility for five business days, contact the seller or ask USPS for a Missing Mail search. A package that left and then arrived at the same facility again was usually mis-sorted and is being sent back on track.
Other messages: every common tracking status, A to Z.