Readville's pretty far south, but it's not that far south, is it?

I saw that a few months ago while driving around. There's no way that was there before the intersection was rebuilt.

EDIT- dperry gave us a great history. I will double down and say that 2008 is still "new," especially considering how old it actually is.

Update: And I stand corrected. How exciting to find out that it is indeed old.

This is a curious thing. This is actually a "new" marker designed to look like mileage markers of yore. I think it says "32" Km which is, as you correctly state, almost 20 miles. Now, from my house to Providence, RI is about 37 miles as the crow flies (which is about 1/4 mile from the marker) so I stand in puzzlement with you.

I can't speak specifically to this marker or where it is, but there are a bunch of them around.

The posts date to the 1830's, and were placed during the original construction of the Boston and Providence Railroad.

Why Km and not miles? Harry Chase speculates about this in his history of the railroad:

http://doddcenter.uconn.edu/asc/findaids/Chase/uconn_asc_2003-0037_007.pdf

MIXED TRAIN TO PROVIDENCE: A HISTORY OF THE BOSTON AND PROVIDENCE RAIL ROAD, THE TAUNTON BRANCH RAIL ROAD, AND CONNECTING LINES, WITH EMPHASIS ON MANSFIELD, MASSACHUSETTS
HARRY B. CHASE, JR.
MANSFIELD, MASSACHUSETTS
2006

from page 77:

"We learn from a secondary source[38] that when Captain William Gibbs McNeill built the railroad he set the kilometer-posts along the way. If we assume, despite some circumstantial evidence to the contrary, that this was so, we must ask “Why?” It‟s possible that through his West Point education or his visit abroad, McNeill became quite properly enamored of the un-American but more practical kilometers instead of miles. The metric system was not entirely foreign to the United States. The U. S. Coast Survey in the early 1800s used meters and kilograms, and Presidents Jefferson and John Quincy Adams favored adoption of the system. It was unquestionably the way to go, and it's a pity succeeding generations didn't follow the lead of whoever introduced kilometer posts on the Boston and Providence. The story is that pressure
brought to bear by the conservative public or the railroad‟s board of directors unfortunately forced the newfangled and unacceptably foreign kilometer markers to be uprooted and replaced by mileposts. But not all were uprooted!
One kilometer post still existed in 1982 in Readville on the Dedham Branch. It read:
B.
48
Km
29.82
M.
This marker and its location were first reported by Jim Zwicker.[39] It appears to be in the wrong place: the mileage from Boston ("B") suggests that it was moved from the main line somewhere just north of Attleborough, perhaps by a history-conscious employe who recognized it as an artifact worth saving, maybe after it had been uprooted by a track gang."

Whenever I think of markers like this, I'm reminded of this Newton/Waltham border marker near us, that's right in front of someone's driveway.

https://goo.gl/maps/GpHWzHeiUUt

From page 706 of the aforementioned book:

A sixth post is in Readville near the intersection of West Milton St. and Sprague St., in a flower bed.
Prov.
32
Km.
19.88
M.

This post was moved recently to its present location. In Aug. 2008 M. Fitzhenry, who grew up near the Readville shops, stated that this post previously had been situated next to the north side of the pier supporting the two spans of the old Sprague St. Bridge, now demolished. The railroad track nearest the post was the lead into the locomotive shop, and the inscription on the post faced that track, the car shop leads, and the “Midway.” In 2006 R. Fleischer and L. Schneider visited the Sprague St. bridge following a report of a kilometer post at Readville near the Dedham branch, but due to the location of the post under the bridge, they did not see it. During construction of the new Sprague St. bridge, Fleischer was informed that the post was lying on its side on wood blocks on a lower level under the bridge. Fitzhenry confirmed
that this post is the same one now situated in the street level flower bed. (R. Fleischer pers. comm. 2008.)
The distance of 19.88 miles from Providence Union Station would place the original location of the post about 1.0 mile north (present “east”) of Mansfield station. When and why it was removed to Readville is not known.

And keep reading pages 706-708 for an interesting discussion / speculation about the origin of the Km posts.

And since a king's mile is not an actual measurable distance, it's precisely the unit of measurement a contractor convinced the state to etch into our distance markers. Some things never change.