usps next day mail rates refer to the pricing for USPS’s Priority Mail Express service, which guarantees next-day delivery to most locations in the United States. The rates for this service vary based on the weight, size, and destination of the package. For a typical shipment, the starting rate for USPS Priority Mail Express is around $26.35, but it increases with package weight and destination. This service includes tracking, insurance up to $100, and a money-back guarantee if the package is not delivered on time. USPS also offers flat-rate options for Priority Mail Express, which can be cost-effective for heavier items.