In late July 1917, the segment from El Paso, to near Lobo was rerouted to instead go to a proposed New Mexico crossing, due south into Van Horn, via SH 54 and continued to near Valentine, Texas over US 90. By 1919, the road again was proposed to bypass Big Bend, meeting up again with current US 90 in Sanderson, meeting up with its old alignment in Langtry. By 1919, SH 12 then terminated far short of Orange in Rosenberg. Much like other highways at the time, multiple alternate routings have been created using the same number, and SH 12 was no exception. SH 12A was designated on December 17, 1918 via present day SH 60 from Wharton to Matagorda.SH 12B was designated on March 18, 1919, from Beeville through Oakville, Tilden, and Gardendale, to Eagle Pass as a bypass if SH 12 between these places could not be built.