I have no source for this other than my own tracking of Clarity VIN numbers which I have been tracking online for quite a while now. As reported previously no 2019's exist outside of the ZEV states (CA/OR and east coast states). If there are exceptions they are extremely rare. Outside of ZEV states only 2018's have been available, however most of those have now been snapped up due to heavy discounting. Also for some reason apparently Oregon stopped receiving shipments a few months ago even though they are a ZEV state, even more mystifying since Oregon is one of only two states (the other being California) where Honda currently offers a $5,000 dealer incentive for Clarity.
As it turns out it's not just Oregon, I discovered today looking through VIN numbers on dealer lots that none of the east coast ZEV states have been receiving 2019 shipments for several months. I didn't notice that earlier because unlike Oregon there are many 2019's on the lots in east coast states.
There was a rumor here a few weeks ago that Honda has stopped producing 2019's, however I still continue to see new VIN numbers appear, although I had noticed that I was seeing them only in California. The latest and highest VIN number that I have found is 004884, which is way below pace compared to 2018, which is no surprise based on the sales figures.
The discovery that I made today was that all east coast cars that I look at have VIN numbers well below 001000 which means production in December/January, maybe February at the latest. All cars built since then have apparently been going exclusively to California.
Note that these are my own opinions based on what I have been seeing on dealer lots, and certainly I have no way to verify every single car, however the evidence seems pretty conclusive.
This could simply be that since production has been slowed for whatever reason (battery supply?) cars for now are only being shipped to California, and sometime in the future either this year or next year they will resume shipments to the other ZEV states. Perhaps that won't happen until the 2020 release, assuming that takes place. However there is also the possibility that the nationwide experiment is over and Clarity will go back to being a California only car, at least for the time being.
Unlike many I believe that Honda is fully committed to PHEV, the question is how does Clarity now fit into that strategy. Reviews and customer experience have for the most part been very positive, but there is also a strong consensus that Honda misstepped by using the older infotainment system on their flagship tech car, as well as the polarizing styling, and a decision to go with a sedan rather than a hatchback. Software glitches didn't help as they resulted in an unfair (by our opinion) poor quality score by Consumer Reports. And of course lack of marketing which was either caused, or the result of poor sales (sort of a chicken and the egg question). Infotainment, styling, and other quibbles can be relatively easily corrected in a refresh, however I think it's a bit soon for that. So my suspicion is that Clarity will go back to being a California car for now, and a decision will be made later if they want to update it and try it again at the national level.
I am hoping to be proved wrong, my opinions are based only on what I am seeing at the moment, hopefully things will change.