What is the premier shipping service offered by the USPS?

The premier shipping service offered by the USPS is Express Mail. This service is designed for time-sensitive shipments and guarantees overnight delivery to most U.S. locations. Express Mail provides features such as tracking, delivery updates, and insurance coverage for valuable items, making it the fastest shipping option available from the USPS.

The other shipping services listed serve different purposes. Priority Mail is a reliable and faster-than-average service but does not provide the same speed guarantee as Express Mail. Parcel Post, now known as Retail Ground, is an economical option mainly for heavier packages but lacks the speed of Express services. First-Class Mail is primarily intended for letters, small packages, and postcards, again not matching the expedited service that Express Mail offers. Therefore, Express Mail stands out as the top choice for those in need of the fastest delivery options from the USPS.