overnight postal rates refer to the cost of shipping a package overnight through various postal services, with the United States Postal Service (USPS) offering a range of options for urgent deliveries. USPS offers the Priority Mail Express service, which guarantees overnight delivery to most destinations within the United States. The cost of overnight shipping varies depending on the size, weight, and destination of the package. USPS Priority Mail Express rates are higher than regular Priority Mail but come with added benefits such as guaranteed delivery by 10:30 AM the next day and insurance coverage for up to $100. Other postal services like UPS and FedEx also provide overnight shipping options, with UPS offering Next Day Air and FedEx providing Priority Overnight, each with its own set of features, costs, and delivery guarantees. When choosing an overnight shipping service, it’s important to compare the rates and delivery times to find the best option.