The next section of that law above explains what happens for folks who already lived in the city and had a pitbull at the time the law was enacted.

Here is the link I used to find the Pawtucket law. This is set for RI, so it shows other links in my state. You can change the state for the search, to find more laws.
http://www.dogsbite.org/legislating-...ode-island.htm