Between January and June 1918, 50,000 men arrived at Camp Travis, but departures aggregated 35,000.

In late August, the 90th Division entered the front lines, participating in the Battle of St. Mihiel in September and the Meuse-Argonne Offensive in October–November 1918.

The headquarters was relocated once more in July 1926 to the Alamo Building in San Antonio and remained there until activated for World War II.

On a number of occasions, the division headquarters and staff, and occasionally the division's three brigade headquarters, participated in Eighth Corps Area and Third Army command post exercises in conjunction with other Regular Army, National Guard, and Organized Reserve units.

Unlike the Regular and Guard units in the Eighth Corps Area, the 90th Division did not participate in the various Eighth Corps Area maneuvers and the Third Army maneuvers of 1938, 1940, and 1941 as an organized unit due to lack of enlisted personnel and equipment.

The enlisted fillers came from reception centers mostly located in the Northwest, Midwest, and Southwest, but a preponderance of the men were from Fort Sam Houston and Camp Wolters, Texas, and Fort Sill, Oklahoma.

On 12 August, the division drove across the Sarthe River, north and east of Le Mans, and took part in the closing of the Falaise Gap, by reaching 1st Polish Armored Division in Chambois, 19 August.

Elements of the 90th Infantry assaulted and captured the German-held Fort de Koenigsmacker 9–12 November.

On 6 December 1944, the division pushed across the Saar River and established a bridgehead north of Saarlautern (present-day Saarlouis), 6–18 December, but with the outbreak of Gerd von Rundstedt's (Army Group A) drive, the Battle of the Bulge, withdrew to the west bank on 19 December, and went on the defensive until 5 January 1945, when it shifted to the scene of the Ardennes struggle, having been relieved along the Saar River by the 94th Infantry Division.

On 19 February, the division smashed through Siegfried Line fortifications to the Prüm River.

Pursuit continued to the Czech border, 18 April 1945, and into the Sudetes mountain range.

The division was en route to Prague when they came upon the remaining 1500 emaciated prisoners left behind by the SS at Flossenbürg concentration camp.