 The Kent @-@ Kangley Road was built as a wagon road by King County by the late 1890s and was upgraded to a paved highway after being codified as two highways during the creation of the primary and secondary state highways system in 1937 : SSH 1K and SSH 5A . SSH 1K traveled 12 @.@ 76 miles ( 20 @.@ 54 km ) south from U.S. Route 99 and Primary State Highway 1 ( PSH 1 ) through <unk> and east through Des Moines to US 99 and PSH 1 in Midway . SSH 5A traveled 14 @.@ 50 miles ( 23 @.@ 34 km ) east from US 99 and PSH 1 in Midway across the Green River into Kent , intersecting SSH <unk> , PSH 5 , and SSH <unk> , before ending at the <unk> – <unk> branch of PSH 5 in Maple Valley . The two highways were combined during the 1964 highway renumbering to form SR 516 and codified into law in 1970 . The highway traveled east from SR 509 in Des Moines through I @-@ 5 at Midway , SR 167 in Kent , and SR 18 in Covington to SR 169 in Maple Valley . SR 509 was re @-@ aligned in 1991 onto SR 516 and SR 99 , forming new <unk> , until the completion of a new north – south freeway . 
