Who delivers for Purolator in the US?

[a52split]

I've got an item to ship from Canada to the US via Purolator. As I was about to buy the label, my buyer gave me a street address for delivery by UPS or FedEx, and a PO Box address if by USPS. I suspect Purolator hands off the package to the USPS for delivery in the US, but I can't confirm this anywhere on the Purolator site or the interweb.

A previous item I shipped by Purolator last summer to a buyer in the US arrived as expected. I thought If I ran that tracking number through the USPS site, it would confirm my suspicions, but the USPS didn't recognise the tracking number. Tracking on the Purolator site gives no clues.

Does anyone know this bit of trivia?

[msau4301 · Accepted solution]

I believe UPS (not USPS) handles Purolator's packages in the US.

I know Canada Post owns Purolator and it would seem like USPS would take over in US but I have heard it is actually UPS (unless that has changed). I know even here in Canada I've had a couple of things delivered this week by UPS that normally come by Canada Post also. My parents had a cable box delivered yesterday that had been given a Canada Post tracking number ("a label was created") last Friday, but arrived by UPS this week. I was glad to see some items are being quickly handled by other sources even here.