Does any know, or have a theory as to why a portage is called a “carry” in the Adirondacks;and seemingly nowhere else?

Not me…

Portages (which is both an English & a French word, but pronounced differently) is also called a carry in the BWCA and other areas I have paddled. So, don’t think it is unique to New York.

Why Is It Called A "Carry?"
Why is it called a “carry” in the Adirondacks? Because that’s what you do.

I have no idea why the rest of the country hasn’t noticed the obvious.

Ever “Hump” your boat…?

no but
I saw a cute sheep once…

Portage is a French word meaning carry. I’m guessing it was used by the French fur traders who did business throughout the northern and mid-western lakes and the name has stuck. It’s probably just a fluke that in some places they use “carry” as opposed to “portage” and vice versa. We have too much time on our hands if we’re thinking about this. Thank god the weather is starting to get better.

Actually, “Carry” is used elsewhere…
…a couple of examples that come quickly to mind being Northeast Carry and Mud Pond Carry in ME.