This can be inferred in FM 7-40, the Field Manual for Rifle Regiments. On page 154 it states that a regiment in a defensive position can defend a front of up to 4000 yards in "partially open, rolling terrain" but as little as 2000 yards in "broken, heavily wooded, terrain". Since the 106th was operating with the standard "2 in front, 1 in reserve" deployment of its regiments, a maximum of 8000 yards (4.5 miles) could be covered by the division. FM 7-40, The Rifle Regiment (1942-02-09)
"The width of the sector held by the 106th Infantry Division and the attached 14th Cavalry Group was approximately eighteen air-line miles. When traced on the ground, the line these forces were responsible for defending was actually more than twenty-one miles in length." Hugh M. Cole (1965). "The Ardennes: Battle of the Bulge, chapter 7". Office of the Chief of Military History. Retrieved 24 June 2020.
