How many states and territories have National Guard units?

The National Guard has a presence in all 50 states, alongside the District of Columbia. Each state has its own National Guard units, which serve both a state and federal mission. The District of Columbia maintains a National Guard that operates under similar principles as state National Guards, providing additional support in times of need, such as during emergencies or for ceremonial duties.

This correct option reflects the comprehensive reach of the National Guard across the entire United States, ensuring all regions have access to this important reserve force. The understanding of this structure is crucial for interpreting how the National Guard can mobilize for various missions, from national defense to local emergency response.