A worker carries a large parcel at the United States Postal Service sorting and processing facility, Thursday, Nov. 18, 2021, in Boston. The U.S Postal Service pulled out all the stops to avoid a repeat of the 2020 holiday shipping disaster, and it worked. The Postal Service and several other private shippers reported that holiday season deliveries went smoothly, for the most part. Credit: AP Photo/Charles Krupa, File

The U.S Postal Service pulled out all the stops to avoid a repeat of the 2020 holiday shipping disaster, and it worked.

The Postal Service and several other private shippers reported that season deliveries went smoothly for the most part.

ShipMatrix, which analyzes shipping package data, reported that 96.9% of the Postal Service's shipments were on time during a two-week period in December. Overall, it was a major improvement across the board compared with last year, when more than a third of first-class mail was late by the time Christmas arrived.

"We're happy to have brought all of the good holiday cheer that we could," said Mark Dimondstein, president of the American Postal Workers Union, which represents more than 200,000 postal workers.

Leading up to the holidays, there were dire warnings of supply chain problems and shipping delays. In the end, shoppers heeded supply chain warnings by ordering and shipping items earlier, while more people opted to shop in stores than the year before, said Satish Jindel, ShipMatrix president in Pennsylvania.

The Postal Service installed 112 new package sorting machines, transitioned more than 60,000 pre-career employees to the ranks of career employees, hired 40,000 seasonal employees and leased extra space at more than 100 locations since last year, officials said.

As a bonus, the number of quarantined postal workers was less than last year, though they're trending upward.

With new standards that extended the deadline on some long-distance mail, the service reported 89.8% of first-class parcels delivered on time through the first 12 weeks of the quarter, and anticipated 12 billion pieces of mail and packages would be delivered between Thanksgiving and New Year's Day.

During the period between Dec. 12-21, UPS and FedEx also saw on-time delivery rates topping 90%, Jindel said. They, too, bolstered their workforces, hiring more than 190,000 additional workers to be better prepared for the holiday peak.

For the U.S. Postal Service, about 6,500 were under COVID-19 quarantine on Christmas Eve, which was better than the year before when 19,000 workers were out at the December peak, according to the American Postal Workers Union.

But those numbers are growing. This week, the number of quarantined workers grew to nearly 8,000, the union said.

Fredric Rolando, president of the National Association of Letter Carriers, said obstacles like the pandemic and quarantines provide staffing challenges, but "they don't alter the mission."

The U.S. Postal Service declined to comment on the quarantine figures, but "we can assure you that the Postal Service does have resources in place, including adequate staffing, to meet the service needs of our customers, now and in the future," said spokesperson Kim Frum.