All American ethnic groups took part in the military effort during WWII. Some of them were not allowed to take as great a part as others (there were segregated units and most blacks weren't put in combat positions, for example), but all of them took part.
As a few examples, we have
- Asians. The Japanese-Americans took part in the war, though they were only allowed to fight in Europe. The 442nd Regimental Combat Team is the most famous example.
- Native Americans. The Navajo "Code Talkers" are the most famous example of this.
- Hispanics. They were not segregated in their own units like blacks and the Japanese-Americans, but many served. 12 Hispanics won the Medal of Honor in the war.