My (Unsubstaniated) Theory...
My theory regarding the Morris serial numbers is that the numbering system we commonly see (4 or 5 digits on an oval or rectangular brass plate) began when Morris began calling his canoes "Type A, Model 1" and so on, rather than "Indian" etc... in other words, in approximately 1902. So, the other sn theory--using the first digit or two of the serial number to date the canoe-- sort of worked, but it was coincidental: there was that thing about the factory fire in 1920 and the serial numbers being 17-series, which called this theory to question. However, if they didn't begin this system of numbering until 1902 (or so), it works.... because 1920 wasn't a true production year for the Morris factory, which burned in the first few days of 1920... so the 17-series boats most likely were built in 1919.
Eventually, other Morris boats may show up in our database to either substantiate what we are now seeing or give us a different perspective...
Anyway, this is cool cool cool. Thanks for the chart, Benson!