I found 2 more shortly after I took that photo.
We brought them down from the attic after power had been out for 8 hours, planning to move the chest freezer to Brian's new place where the power was still on. Luckily, power returned just before we started loading. After returning them all to the attic, one by one, I made this solemn vow:
They get stored in the carriage house from now on. Coolers don't go up stairs anymore in the Sullivan House.