That's funny...
I had two ladies (older and a younger one) yelling at me that it was against the Law to ride on the Sidewalks in my Town. Then the younger one told me of her friend on a bike got hit in the road. Duh.

I told them both to check with the Police Department (I had), if there is no Sign or Markings it is legal.
Which means every sidewalk in my town is legal.
There are a few Grocery Stores or Department Stores that have signs: NO Rollerblading, NO Skateboarding, No Bicycling.

Like I said, I tend to stay on the Pavement, Sidewalks are there if we need them!