Army National Guard in the context of Tim Walz

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.

The Air National Guard (ANG), also known as the Air Guard, is a federal military reserve force of the United States Air Force (USAF), as well as the "air militia" of each U.S. state, the District of Columbia, the Commonwealth of Puerto Rico, and the territories of Guam and the U.S. Virgin Islands. It, along with the Army National Guard component of each state, district, commonwealth or territory, makes up the National Guard of each region as applicable. Additionally, the ANG and the United States Air Force Reserve constitute the two air reserve components of the USAF.

When Air National Guard units are used under the jurisdiction of the state governor they are fulfilling their militia role. However, when federalized by order of the president of the United States, ANG units become an active part of the U.S. Air Force. They are jointly administered by the states and the National Guard Bureau, a joint bureau of the Army and Air Force that oversees the U.S. National Guard.

The Virgin Islands National Guard (VING) is a component of the United States Armed Forces' National Guard based in the United States Virgin Islands. It was established on October 19, 1973 in a ceremony officiated by Major-General La Vern E. Weber, then serving as the director of the Army National Guard. Major Leayle Galiber was concurrently appointed as acting Adjutant-General and took command of the first two VING units to be activated, a headquarters detachment and the 661st Military Police Company, both of which were stationed on the island of Saint Croix.

The Active Guard and Reserve (AGR) is a United States Army and United States Air Force federal military program which places Army National Guard and Army Reserve soldiers and Air National Guard and Air Force Reserve airmen on federal active duty status under Title 10 U.S.C., or full-time National Guard duty under Title 32 U.S.C. 502(f) for a period of 180 consecutive days or greater in order to provide full-time support to National Guard and Reserve organizations for the purpose of leading, organizing, administering, recruiting, instructing, or training the Reserve Components according to Subsection 101(d)(6). AGR personnel may also be assigned to active duty roles in support of Regular Army and Regular Air Force organizations or joint organizations such as the Office of the Secretary of Defense, Secretary of the Army, Secretary of the Air Force, the Joint Staff, or the Unified Combatant Commands.

The chief of the National Guard Bureau (CNGB) is the highest-ranking officer of the National Guard and the head of the National Guard Bureau. The position is a statutory office (10 U.S.C. § 10502), held by a federally recognized commissioned officer who has served at least 10 years of federally recognized active duty in the National Guard; the Army National Guard or the Air National Guard. In a separate capacity as a member of the Joint Chiefs of Staff (10 U.S.C. § 151), the chief is a military adviser to the National Security Council, the Homeland Security Council, the secretary of defense, and the president on matters pertaining to the National Guard.

The chief is nominated for appointment by the president from any eligible National Guard officers holding the rank of major general or above, who also meets the requirements for the position as determined by defense secretary and the chairman of the Joint Chiefs of Staff, under the advice and/or recommendation from their respective state governors and their service secretary. The chief and vice chief of the National Guard Bureau cannot be from the same service. The nominee must be confirmed via majority vote from the Senate. The chief serves a four-year term of office at the pleasure of the president. By statute, the Chief is appointed as a four-star general in the Army or Air Force, serving as a reserve officer on active duty.

The United States Army Forces Command (FORSCOM) was the largest command of the United States Army. It provided land forces to the Department of Defense's unified combatant commands. FORSCOM was headquartered at Fort Bragg, North Carolina, and consisted of more than 750,000 active Army, U.S. Army Reserve, and Army National Guard soldiers. It was created on 1 July 1973 from the former Continental Army Command (CONARC), which in turn supplanted Army Field Forces and Army Ground Forces.

FORSCOM was disestablished on 5 December 2025, the same time as the Army standing up U.S. Army Western Hemisphere Command (USAWHC).

The Illinois National Guard comprises both Army National Guard and Air National Guard components of Illinois. As of 2013, the Illinois National Guard has approximately 13,200 members. The National Guard is the only United States military force empowered to function in a state status. The Constitution of the United States specifically charges the National Guard with dual federal and state missions. Those functions range from limited actions during non-emergency situations to full scale law enforcement of martial law when local law enforcement officials can no longer maintain civil control. The National Guard may be called into federal service in response to a call by the President or Congress.

The 29th Infantry Division (29th ID), also known as the "Blue and Gray Division", is an infantry division of the United States Army based at Fort Belvoir in Fairfax County, Virginia. The division is currently a formation of the Army National Guard and includes units from Virginia, Maryland, Kentucky, North Carolina, South Carolina, and West Virginia.

Formed in 1917, the division deployed to France as a part of the American Expeditionary Force during World War I. It was called up for service again during World War II. The division's 116th Regiment, attached to the First Infantry Division, was the first wave of troops ashore during Operation Overlord, the landings in Normandy, France. It supported a special Ranger unit tasked with clearing strong points at Omaha Beach. The rest of the 29th ID came ashore later, then advanced to Saint-Lô, and eventually through France and into Germany.

The Army Medical Department of the U.S. Army (AMEDD), formerly known as the Army Medical Service (AMS), encompasses the Army's six medical Special Branches (or "Corps"). It was established as the "Army Hospital" in July 1775 to coordinate the medical care required by the Continental Army during the Revolutionary War. The AMEDD is led by the Surgeon General of the U.S. Army, a lieutenant general.

The AMEDD is the U.S. Army's healthcare organization (as opposed to an Army Command), and is present in the Active Army, the U.S. Army Reserve, and the Army National Guard components. It is headquartered at Fort Sam Houston, San Antonio, Texas, which hosts the AMEDD Center and School (AMEDDC&S). Large numbers of AMEDD senior leaders can also be found in the Washington D.C. area, divided between the Pentagon and the Walter Reed National Military Medical Center (WRNMMC).