Army National Guard in the context of "Virgin Islands National Guard"

The United States Army (U.S. Army) is the land service branch of the United States Armed Forces. It is designated as the Army of the United States in the United States Constitution. It operates under the authority, direction, and control of the United States secretary of defense. As a part of the United States Department of Defense, it is one of the six armed forces of the United States and one of the eight uniformed services of the United States. The Army is the most senior branch in order of precedence amongst the armed services. It has its roots in the Continental Army, formed on 14 June 1775 to fight against the British for independence during the American Revolutionary War (1775–1783). After the Revolutionary War, the Congress of the Confederation created the United States Army on 3 June 1784 to replace the disbanded Continental Army.

The U.S. Army is part of the Department of the Army, which is one of the three military departments of the Department of Defense. The U.S. Army is headed by a civilian senior appointed civil servant, the secretary of the Army (SECARMY), and by a chief military officer, the chief of staff of the Army (CSA) who is a member of the Joint Chiefs of Staff. It is the largest military branch, and in the fiscal year 2022, the projected end strength for the Regular Army (USA) was 480,893 soldiers; the Army National Guard (ARNG) had 336,129 soldiers and the U.S. Army Reserve (USAR) had 188,703 soldiers; the combined-component strength of the U.S. Army was 1,005,725 soldiers. The Army's mission is "to fight and win our Nation's wars, by providing prompt, sustained land dominance, across the full range of military operations and the spectrum of conflict, in support of combatant commanders". The branch participates in conflicts worldwide and is the major ground-based offensive and defensive force of the United States of America.‌

The United States Army Reserve (USAR) is a reserve force of the United States Army. Together, the Army Reserve and the Army National Guard constitute the Army element of the reserve components of the United States Armed Forces.

The Regular Army of the United States succeeded the Continental Army as the country's permanent, professional land-based military force. In modern times, the professional core of the United States Army continues to be called the Regular Army (often abbreviated as "RA"). From the time of the American Revolution until after the Spanish–American War, state militias and volunteer regiments organized by the states (but thereafter controlled by federal authorities and federal generals in time of war) supported the smaller Regular Army of the United States. These volunteer regiments came to be called United States Volunteers (USV) in contrast to the Regular United States Army (USA). During the American Civil War, about 97 percent of the Union Army was United States Volunteers.

In contemporary use, the term Regular Army refers to the full-time active component of the United States Army, as distinguished from the Army Reserve and the Army National Guard. A fourth component, the Army of the United States, has been inactive since the suspension of the draft in 1973 and the U.S. armed forces became an all-volunteer armed force.

The 42nd Infantry Division (42ID) ("Rainbow") is a division of the United States Army National Guard. It was nicknamed the Rainbow Division because, during rapid mobilization for service in WWI, it was formed from 27 National Guard units from across the US. The division was engaged in four major operations between July 1918 and the armistice in November 1918, and demobilized in 1919. Since World War I, the 42nd Infantry Division has served in World War II and the global war on terrorism (GWOT).

The division is currently headquartered at the Glenmore Road Armory in Troy, New York. The division headquarters is a unit of the New York Army National Guard. The division currently includes Army National Guard units from fourteen different states, including Connecticut, Maine, Maryland, Massachusetts, Michigan, New Hampshire, New Jersey, New York, Rhode Island, and Vermont. As of 2007, 67 percent of 42ID soldiers are located in New York and New Jersey.

The 27th Infantry Division was a unit of the Army National Guard in World War I and World War II. The division traces its history from the New York Division, formed originally in 1908. The 6th Division designation was changed to the 27th Division in July 1917.

In the United States, state defense forces (SDFs) are military units that operate under the sole authority of a state government. State defense forces are authorized by state and federal law and are under the command of the governor of each state.

State defense forces are distinct from their state's National Guard in that they cannot become federal entities. All state National Guard personnel (including the National Guard of the District of Columbia, the Commonwealth of Puerto Rico and the territories of Guam and the Virgin Islands) can be federalized under the National Defense Act Amendments of 1933 with the creation of the National Guard of the United States. This provides the basis for integrating units and personnel of the Army National Guard into the U.S. Army and, since 1947, units and personnel of the Air National Guard into the U.S. Air Force.

The Kansas Army National Guard is a component of the Army National Guard and the Kansas National Guard. Kansas Army National Guard units are trained and equipped as part of the United States Army. The same ranks and insignia are used and National Guardsmen are eligible to receive all United States military awards. The Kansas Guard also bestows a number of state awards for local services rendered in or to the state of Kansas. It is, along with the Kansas Air National Guard, an element of the Kansas National Guard.