The delivery time for the USPS is according to the class:
For the first-Class Mail it is 1-3 business days. For Priority it is Mail 1-3 business days. 1-2 Days Guaranteed with Priority Mail Express. Express Marketing Mail: 2–10 days
Depending on the individual service being used and the sender’s and recipient’s locations, USPS delivery timeframes vary. First Class Mail delivery often takes 1-3 business days, Priority Mail delivery usually takes 1-3 business days. Priority Mail Express guarantees delivery in 1-2 days. Marketing Mail Express: 2-10 business days.