By Gary Campbell

The sidewalks of Toronto are littered with contractor stamps. They’re so common that we’ve stopped noticing them completely — but walk ten feet in any direction and you’ll stumble over two or three.
What are they? Paving workers press their official company name and year into the wet concrete at the end of construction. These stamps indicate who put down a given piece of sidewalk and when it was laid. While they’re all roughly the same size, you’ll find quite a lot of variation to the stamp designs — ovals, rectangles, with borders or without…
The city uses the stamps for warranty inspections. If there’s a fault with a piece of sidewalk concrete, the city can quickly identify the firm responsible. [ed. note. We've heard that the city actually hires someone to catalogue sidewalk stamps so they can identify which contractors are doing substandard work!]
However, at intersections where there are dozens of them, the stamps also act as little promotional advertisements for a given contractor. Are there other public works projects where workers are so visibly “signing” their work? Whomever paints lines on the road isn’t reversing their logo out of every fifth stripe.
Contrast this with the sidewalks of New York where contractor stamps are virtually non-existent.
Extra marks: Need to occupy kids or friends with OCD? Send them off to seek out the oldest and newest stamps on your block.