Some of PG&E’s access covers have dates on them. These two examples are on 20th Street near Broadway, and you can see the subtle differences in the designs from 1969 and 2011.
These aren’t the same thing as a sidewalk stamp. These dates are presumably the day the covers were manufactured, not the day they were lowered into place on the street. Indeed, the older lid may have been used somewhere else for many years. We’ll never know. Whereas sidewalk stamps bear the dates they were created, like a newspaper.
Oakland Underfoot 