 The Forest Highway System was created by the Federal Aid Highway Act of 1921 . An earthen road was present along the route of H @-@ 13 by the middle of 1936 . Later that year , the segment along the Alger – Schoolcraft county line was built as a gravel road , and Miners Castle Road was upgraded to gravel as well . Additional segments were under construction in 1940 in Delta County and south of Wetmore . During World War II , the gravel surface was downgraded to earth along Miners Castle Road . The rest of the modern H @-@ 13 was paved in 1948 or 1949 . 
