American Uniforms
American uniforms from World War I did not vary incredibly. Most divisions had similar style tunics and pants with different details depending on the division and rank of the soldier.
Army
U.S. Army Summer Tunic
The U.S. Army used different uniforms within the division. There was a summer uniform and a winter uniform along with many others. The summer tunic is made of a canvas-like material with brass buttons while the pants are lined with wool and made to accommodate horse-riding. The winter uniform is made of wool and cotton to keep the soldiers warm in battle (Quanonline).
Aviation
U.S Air Service Tunic
The U.S. Aviation division was just starting out, therefore, the uniforms were mostly army issued with Air Service decorations. The tunic pictured was an Army tunic with decorations indicating an Air Service soldier. The soldier belonged to the 3rd Air Corps as seen by the patch on the upper left sleeve with the number three.