How can i track USPS Post Starting With Code US ?

USPS Express Mail Tracking, the only service that offers tracking, as well as Confirmation and Customs numbers do not start with US.
Originating numbers will end in US. This designates the country of origin according to Universal Postal Union regulation. There is also no USPS numbering Tracking that has any letters in the middle. Either your friend is not using USPS or their national Postal Service, or they have made a couple of typos in sending you the number.