Just finished up working up my photos from Badlands National Park for the Surewhynotnow blog site. Open question, when exactly was US 16A applied to the Badlands Loop Road? From everything I read it looks like US 16A was first sometime between 1944 and 1949:
http://surewhynotnow.blogspot.com/2018/09/2016-summer-mountain-trip-badlands.html