USPS has busiest day of year

"Our employees work tirelessly to make sure cards and packages arrive on time for the holidays," Postmaster General Patrick Donahoe said in a statement, noting the service's "237 years of experience."

With less than a month left in the current Congress, key lawmakers from both parties and both chambers are meeting to see if they can hash out compromise legislation to overhaul postal operations. 

Donahoe has said the agency needs to cut $22.5 billion in annual costs by 2016.