Contractors stamp their company name and the date into the wet concrete of a sidewalk.
In Toronto, these stamps are all over. This is, apparently, so the city
can quickly identify the company responsible if there is a fault with the
concrete.

I hear the stamps are not as common in the U.S. (virtually non-existent in New York?).
According to the UC Berkeley archive of contractor stamps, they are on the wane because of increasing concern about litigation.
I think this says something fairly fundamental about the difference between our
two nations.
I'm not sure it's particularly flattering for either.