If you're mailing a letter, it could be sent by UPS.
The U.S. Postal Service is partnering with with United Parcel Service.
A new agreement announced yesterday means UPS will fly mail between 98 U.S. cities.
The Postal Service says customers won't see a chance in the way mail is delivered as a result of the pact.
The deal covers first-class and priority mail.
UPS calls itself the world's largest package delivery company.