Lee,
Below is a good page showing the organizational chart of the 100th Infantry Divison and is typical of all US infantry divisions from 1944 on. Special units were added as needed, especially Tank/Tank Destroyer Battalions and Automatic AA Weapons battalions. These additions were more common in the ETO than the PTO. As a result of this added battalions, US infantry divisions late in the war often had more armor than did a German panzer division and upped the number of men in the infantry division to around 20,000 men.
100th Division
Click on formations on the page to show details
Here is another page
United States Army Divisional Organisations
Back the previous page to it's home page
Battalion Organisation During WWII