Major part of enemy activities along American east coast according to the U.S. Joint Intelligence Committee. Daily summary dated 17 April 1942

An item reported that the main part of enemy submarine activities in the western part of the Atlantic theater still concentrated along the USA east coast in the general vicinity of Cape Hatteras. 

Source

Map Room Papers (Roosevelt Administration), 1942 - 1945. U.S. Joint Intelligence Committee. Daily summary No. 128 dated 17 April 1942