We have roughly 6,000 flat sorting machines. They operate about 17 hours per day. They handle 35,000 pieces of flat mail per hour.
But let's be conservative and assume it's:
30,000 pieces per hour
8 hours a day.
To save you the math, that's 1.2 Billion pieces a day, running at less than half of average.
The Postal Service processes and delivers 472.1 million mail pieces each day. We have a lot of excess capacity.
Unfortunately, there is no one article that provides all of that. Here are a few that provide the stats above, and I have verified it with other articles over the months:
Or you can simplify a bit of the math from this statement by the American Postal Workers Union (which should know):
"According to a grievance filed by the American Postal Workers Union and obtained by The Washington Post, the USPS was poised to decommission 671 of the massive machines, roughly 10% of its inventory, and capable of sorting 21.4 million pieces of paper mail per hour. The Postal Service, by comparison, processes as much as 500 million items each day.
I'd suggest questioning a lot of stuff you read on the internet.