Officially known as Joint Base Lewis-McChord (combining the Army's Fort Lewis and the Air Force's McChord AFB) the original Army installation was founded in 1917. Joint Base Lewis-McChord (JBLM) tenant units for the US Army include the US Army I Corps, including numerous infantry, medical, engineer, and support personnel. JBLM contains more than 86,000 acres with more than 25,000 soliders and civilians working on base.

Built in 1900, originally Fort Lawton was planned to help defend the area around Seattle from a naval attack. It was used during World War II as both a training area and a POW camp, and also during the Korean War as a processing location for returning soldiers.

Fort Lawton was officially closed on September 14, 2011 with the last Army Reserve unit leaving and the property being transferred to the city of Seattle sometime in 2012.

Established in 1914, Fort Story; previously a sub-installation of Fort Eustis, is now a sub-installation of US Navy Little Creek Amphibious Base. Because of its location at the entrance to Chesapeake Bay, Fort Story contains a mixture of both soft and hard sand beaches, grassy dunes and cyprus swamps. Because of these natural features it is commonly used by Army for training in amphibious and Joint Logistics-Over-the-Shore (LOTS) training.

Established in 1916, Fort Eustis is primarily used as a logistics, deployment, and maintenance facility. As of 2005, it is a joint facility incorporating operations from US Air Force Base Langley. It is also the home to the US Army Training and Doctrine Command (TRADOC), the Army Aviation Applied Technology Directorate, and the Army Training Support Center.