Amazon recently announced plans to use the postal service to deliver packages to U.S. customers seven days a week.
Amazon will launch the new Sunday service in the Los Angeles and New York metropolitan areas immediately, just in time for the holiday shopping rush. The rest of the country will follow suit in 2014.
To handle the additional mail load, the Postal Service will use its flexible scheduling of employees, USPS spokeswoman Sue Brennan said. The USPS isn’t planning to hire additional workers.
The partnership is expected to help the Postal Service financially, which lost $16 billion last year.