Which USPS service is best for urgent items that need to be delivered overnight?

The correct choice for urgent items that require overnight delivery is Priority Mail Express. This service is designed specifically for time-sensitive deliveries, offering guaranteed delivery overnight to most locations in the United States. It includes additional features such as tracking and free package pickup, which enhance its reliability and convenience for urgent shipping needs.

Priority Mail is typically a next-day or two-day service, but it does not guarantee overnight delivery to all areas, making it less suitable for urgent items that require immediate attention. Standard Post, now known as Retail Ground, is a more economical choice for less time-sensitive mail and can take several days for delivery. First-Class Mail generally provides quicker delivery for lightweight items, but it also does not guarantee overnight service and is better suited for letters and small parcels.

Thus, for anyone needing to send an urgent item that must arrive by the next day, Priority Mail Express is the most appropriate choice.