It fell to 10% in 1941 because of jobs created for the Lend-Lease program, declined further after the U.S. sent troops into battle, and by the war's end stood at 2%.
It is so serious that the wall was never even approached when President Lincoln suspended the writ of habeas corpus, nor when President Roosevelt misled the public about the involvement in the Lend-Lease Program, nor when President Reagan misled the country and Congress about involvement with Iran-Contra.