Origin of stone mile markers on Route 9 in NY's Hudson Valley

Factual Questions
1

Driving north on Route 9 through Dutchess and Columbia County today, I again noticed the stone mile markers along the western side of the road. They mark the distance from New York City (the one I often pass says “118 miles to New York”) and seem to be placed completely at random. They’re made of a single engraved white stone (looks like a headstone), surrounded by fieldstone on either side that support a stone “roof” above.

I don’t think these are markers from Franklin’s original work on the King’s Highway to Boston (this is too far north and out of the way, for one thing, and I thought his markers were far more rudimentary). They strike me more as something nostalgic that someone commissioned in the 60s or 70s.

Anyone know the whens, whys, and whos of this?

2

Thus reads a small round-stopped stone no more than a foot high near the village line between Dobbs Ferry and Irvington, not 1/4 mile from where I’m sitting.

I have no idea whether it’s the real thing or not, but a quick Google search doesn’t reveal that any reproduction milestones have ever been erected along what was once known as the [http://users.bestweb.net/~judynoel/ors/milestones.htm]Old Albany Post Road, renamed US Highway 9 in 1926.

The linked site suggests the OAPR was established by act in 1785 and was fully milemarked by 1789. Postmaster General Ben Franklin may or may not have measured the route himself.

3

Corrected link: http://users.bestweb.net/~judynoel/ors/milestones.htm