us post office overnight cutoff time The USPS overnight cutoff time refers to the latest time you can drop off an item at the post office to ensure it will be delivered the next day using the Priority Mail Express service. The cutoff time varies by location and is typically set by the local post office, with many locations having cutoff times as late as 5 p.m. or 6 p.m. To ensure that your package qualifies for overnight delivery, it is important to check the cutoff times for your local USPS office. Some locations may also offer extended hours or drop-off options to accommodate last-minute shipments.