I agree with the first assessment that it is a New York rifle; it has many of that State's details including the walnut stock, short forestock grip area, checkered wrist, closed loop rear spur on the guard, etc. You can assist us in better identifying the rifle by posting a clear picture of the maker's stamp on top of the barrel a few inches behind the rear sight. Even if worn, we might be able to read the first initial, which would help clarify the specific maker.
These later, rather plain half-stocked New York rifles are not in demand by collectors... but perhaps worth somewhat more if marketed in the area around where the gun was made... if its maker can be identified. However, a limited restoration, i.e. a couple of small repairs, would enhance the value of the gun and make it more saleable. First, have an appropriate era/style percussion hammer put back on the lock [can't tell if tumbler shaft is OK in dark photo], and second, remove the rear ramp sight, straighten it out so it lays flat on the barrel, then replace the lost small "stepped" adjustment bar that is missing... even a relatively new one would help the gun's appearance. I wouldn't do much more since the gun appears to be in generally good shape with an old collector-friendly finish.
Shelby Gallien