From the US Postal Service:
Post Offices Close Early on Christmas Eve and New Year’s Eve.
Post Offices nationwide will be open on Christmas Eve, Wednesday, Dec. 24, and New Year’s Eve, Wednesday, Dec. 31. Most Post Offices will shorten retail lobby hours and close at noon on these holiday eves. Regular mail delivery for Dec. 24 and 31 will be unaffected by the change.
Revised hours will be posted at each Post Office. If you are a business customer, please check with your Bulk Mail Entry Unit for specific information regarding holiday hours of operation.
Post Offices will be closed Thursday, Dec. 25 and Thursday, Jan. 1. All Post Offices will be open and regular mail delivery will resume on Friday, Dec. 26 and Friday, Jan. 2.
Mail from Blue Collection Boxes May Be Collected Early.
Be sure to deposit your mail into all blue collection boxes by noon on Dec. 24 and 31, regardless of the final collection times posted. This means if the final collection time is already before noon (12 p.m.), there will be no change. However, if the final collection time is normally after noon (12 p.m.), mail may be collected early.
If you require service later on those days, please contact your local Post Office. For contact information, visit Find a Location on USPS.com or call 1-800-ASK-USPS.