The Army National Guard is a part-time state-based military component that serves a dual mission. Each Guard unit serves under the command of their state governor to respond to natural disasters or other state emergencies. In addition, Guard units can be activated to defend the nation when needed.

Each state, Washington D.C. and the U.S. territories of Guam, Puerto Rico, and the Virgin Islands, have their own Army National Guard units. There are 54 units in total.