USPS recycles their tracking numbers

Definitely one of those “that’s interesting” discoveries.

I was curious about an old Ebay purchase I made back in late 2019, and went to look up the tracking number in my Ebay history to see if I could find out what state it originally came from.

Pulling up the history, I saw the tracking number was still in the order history, and that it had originally shipped back on December 27th 2019, and was delivered on January 3rd 2020.

The tracking number was still listed as 9 400 116 901 508 666 357 577, so I copied that number to the USPS website, hoping it would pull up its’ state of origin.

I was VERY surprised to see the tracking number showed the package had been delivered to an address in Washington DC on April 16th 2021. That destination was NOT my shipping address, and both the date and time were completely wrong.

I thought it might be a system error, so I tried looking up my next Ebay purchase.

A simple Keffiyeh I bought back in April 2020. Looking at the order history, I saw another tracking number from USPS and the original shipping date was April 9th 2020 and the delivery date was April 20th 2020.

Heading back to the USPS tracking page, I keyed in 9 400 136 897 846 497 465 686 and found “label created, not yet in system”.

I checked the next Ebay purchase I made. The first season of Chef! from the BBC on September 27th, 2020.

Again, the original order showed it was placed on September 27th 2020, and that it was shipped and delivered on October 1st 2020.

Heading to the USPS tracking page, I keyed in 9 400 108 205 497 360 464 217 and saw the package had just been delivered a few days ago, and was waiting for me at Wyandotte, MI.

The USPS tracking numbers repeated a similar pattern for all the other orders I had placed after the October 2020 date as well. The searches either found a package that was delivered to another address in very recent months, or the label was “created, not yet in system.”

The tracking picked up correctly on an order I placed in March of 2021, but every single tracking number before March 2021 had been recycled or re-queued.

I can only confirm the USPS tracking resets sometime between December 2020 and March 2021, so just as an example, let’s assume there’s an annual tracking number reset.

Quick math…

One of the tracking numbers I was issued is 9,400,108,205,497,360,464,217.

21 zeroes after the one is a sextillion, making 9,999,999,999,999,999,999,999 possible tracking numbers per year (assuming 0,000,000,000,000,000,000,001 is a valid tracking number incrementing all the way up to 9,999,999,999,999,999,999,999.)

9,999,999,999,999,999,999,999 divided by 12 (months) is 8.3333333e+20 or 83,333,333,333,333,333,333.

83 quintillion unique tracking numbers a month!?! And then they have to roll over and re-use 9,999,999,999,999,999,999,999 tracking numbers every year?

That’s almost unbelievable.

Either the post office has an insane amount of traffic flowing through it, there’s a glitch in their system, or there is a “reserved” set of USPS tracking numbers for EBay (in my direct observation case, around 9,400,108,205,497,360,464,217 to around 9,400,116,901,508,666,357,577)