This comment is pedantic. Yes, there are special regulations about homeowners in some areas having to place and maintain sidewalks along their property. (In other areas, they are owned and/or maintained by the city.) That's very distinct from setbacks, which prohibit construction for a depth much further than the width of the sidewalk.

Your lot usually doesn't include the sidewalk or the treelawn for that matter, although you are usually held responsible for its maintenance.