U.S. Service Academies
U.S. Service Academies, also known as Military Academies, are highly competitive, elite 4-year colleges, which are free to attend and require a certain number of years of military service upon graduation. All except for the Coast Guard Academy require a Congressional or other political nomination.
For advice on how to prepare/stand out as a candidate for Service Academies, read this.
The U.S. Service Academies are:
U.S. Military Academy West Point (Army)
*The U.S. Marine Corps falls under the Department of the Navy; as such, prospective Marine Officers are selected from midshipmen and women at the U.S. Naval Academy at Annapolis, Maryland. There is no Marine Corps Academy.