I would imagine that it is illegal to park on the curb or sidewalk where you live. In CA it is illegal to park across a sidewalk impeding pedestrian traffic even if it's your own driveway. They may also consider the sidewalk a fire lane subject to tow away. In CA if you park across even your own drive way you will get towed since they do consider the driveway and anything from beyond the curb a fire access point.

Could this be a city ordinance deal thingy?  No where that I've ever lived have I heard this. Blocking the sidewalk I've heard of, but only to cite you, not tow away (in your own driveway, that is). I guess that would depend on the circumstances. Maybe, say, if you had a truck and trailer combo parked where it stuck out over the sidewalk... Can't say I've ever been cited for it or towed away for that matter nor have I heard of anyone having this happen to them. I suppose that doesn't mean it isn't written somewhere.