Minnesota roadside marker

Minnesota Highway #75 marker.

A number of years ago I drove passed this marker, and having not noticed it before, I backed up and took a couple of photos. This is the south side of it as you drive north and it sits on the west side of the road, just before you cross the railway tracks a few miles north of Humboldt.

View looking south.

The highway sign/monument is built of stone and wood and is tastefully done.  I wish more road signs were built in this manner, but the rockwork would be costly.  I wonder what year it was built.