Map of US highway 17 and family
US 17 is represented by the purple line from Winchester VA to Punta Gorda FL. The blue line shown in South Carolina is Alternate US 17.
US 17-1 (historic) is the red line from Petersburg VA to Wilmington NC.
US 117 [I] (historic) is the red line from Norlina NC to Virginia Beach.
US 217 (historic) is the red line from Wilson NC to Pee Dee SC.
All of these branches of US 17 were among the original routes of 1926, but they were all swallowed up by other routes in 1933. At that time, part of the former US 17-1 was redesignated as US 117 [II], and to this day that is the only remaining branch route off US 17.
US 117 [II] is the blue/red dashed line from Wilmington to Wilson NC.