priority express mail rates are the fees associated with USPS Priority Mail Express, the fastest domestic service offered by the United States Postal Service. This service guarantees overnight delivery, including weekends and holidays, depending on the destination. Priority Mail Express rates vary based on factors such as package weight, size, and destination. For larger or heavier packages, the rates are higher, but the service ensures fast and reliable delivery, making it ideal for urgent shipments. Discounts may also be available for certain business customers.