Local laws, also known as municipal laws or ordinances, are laws enacted by municipal governments. Unfortunately, there is no single database that you can search for all local laws in the US. There are several publishers of municipal codes, and often, municipalities will contract with a specific publisher to publish the print and online versions of their codes. You will have to adjust your research strategies accordingly:
The APA state chapters webpages contain lists of RFPs (Requests for Proposals) and RFQs (Request for Qualifications) from municipalities and other organizations that are looking for hire a consultant to assist with revising a code, writing or updating a comprehensive plan, or other type of plan, etc. Not all municipalities will hire a consultant in all instances, but RFPs and RFQs can be a useful indicator that some significant planning action is being considered by that municipality.