Since the earliest days of the United States, state governments have devolved some of their police powers to counties and municipalities to make local laws affecting matters like zoning, noise pollution, fire safety, public health, and other areas of interest to localities. The legislative bodies of these entities (often called city councils or boards of alderman) enact regulations typically called ordinances to regulate these areas (and other areas delegated to them by the states). These indiviual ordinances are collected into comprehensive codes.
Most cities outsource the publication of codes of ordinances to specialized commercial publishers who sell print copies and publish free online versions on their websites (see below). New ordinances are published on city websites and can usually be found with an easy cityname+ordinances Google search.
(Some codes are published by firms handling only one or a few states. To find links to these regional publishers, see Barbara Bavis, Municipal Codes: A Beginner’s Guide, Law Library of Congress, November 21, 2013, in the Guides box to the right).