It has been approximately 15 years since spray-on cancellations became the norm in the United States. Perhaps the non-spray cancellation machines will soon be extinct, after a decades-long period of service.
As of 2019/2020, any thoughts as to how many of the non-spray machines remain in operation? Perhaps just some low-volume postal distribution facilities? For example, all mail that I have seen from Guam continues to have a non-spray cancel.
Minneapolis seems to have two non-spray machines in operation. By my calculations, less than 1% of Minneapolis mail is canceled by these older machines. All Minneapolis specimens that I have found for 2017, 2018, 2019, and 2020 lack the year within the cancelation circle. Perhaps Minneapolis wants to be Peter Pan's new "Never Never Land."
Furthermore, the machines' components are occasionally assembled wrong. For example, the date might appear upside-down. Perhaps the increase of cancellation errors is triggered by fewer USPS employees familiar with the older machines?
Perhaps in the future I will reply to this thread with my inventory of cancellations that lack the year, plus related oddities.
Disclaimers: I am neither a cancellation expert nor a postal machinery expert. I previously shared this information on a forum that has since disappeared. At that time, someone thought the non-spray cancellation machine was called a "Mark II."