Congress passed authorization for State Defense Forces in 1954, and since then several states have established State Guards or State Defense Forces or State Military Reserves. These are usually also provided for in each state's statutes. 

In each state with recognized State Guards, the State Guard belongs to the office of the Governor; sometimes they are separate forces available to the governor, and sometimes auxiliaries or reserves of the state's National Guard and are directed by the state's Adjutant General. Some states (Colorado, Oklahoma, and Pennsylvania) have State Guards or State Military reserves not recognized in statutes; others (i.e., Florida) are recognized in statutes but not yet officially by the present state government.

State Guards sometimes duplicate the role of the National Guard, sometimes have completely separate and distinct roles, or serve their state somewhere in between. Many serve in Civil Defense or Emergency Management roles.