Unfortunately many of the roads in West and South Texas did not exist as planned (and still don't), and the technology available in 1919 wasn't up to the task of building so many miles of non-existent roadway quickly and efficiently. This led to SH 12 being rerouted many times, each time trying to keep it as a border-to-border highway, hugging the southern borderline. On November 20, 1917, SH 12 was rerouted into Corpus Christi via present day Interstate 37, U.S. Highway 181 and SH 35 into Rockport, Texas. The road then doublebacked, via SH 188 and FM 136 to Bayside. From here, another proposed road would have met back with US 77 into Victoria.