Anyone else realize that lately Amazon has been shipping more and more with USPS as opposed to UPS? Are they changing over their primary carrier?
I think that they sort & ship the items themselves (or some other company), & they only use the USPS for the 'last mile delivery'.
As seen from the tracking it is always 'departed shipping partner facility etc., only the day of the delivery it gets handed over to the post office as you will see the acceptance of the package to the USPS system is at your local post office. Also you can see that even if your Amazon package started out in California, the last destination before getting accepted by the USPS is in Avenel, NJ as this is the closest Amazon sorting facility to where I live.
(this all is said for me that lives in Brooklyn 11219, for those living in other places this could be different)