Laws in the US are made by the legislatures. These are the Congress of the United States and the legislatures of the several States and associated territories such as Puerto Rico. Cities and counties also create laws, but they are more likely to be called by other names, such as "ordinance" or "code."
In addition to this legislative process, law can made by executive action. An agency such as the Department of Justice or the State Health Department can publish a notice of intent to issue a regulation, hold public hearing and then issue a regulation, which is a kind of law.