On March 16, 1937, the section from Hubbard to Munger was cancelled due to a lateral project. This section was restored on October 24, 1938. On October 25, 1938, SH 171 was extended southeast to Mexia along the old route of US 84/SH 7.
On March 16, 1937, the segment from Hubbard to Munger was scrapped due to a parallel undertaking. This section was reinstated on October 24, 1938. On October 25, 1938, SH 171 was prolonged southeast to Mexia along the old route of US 84/SH 7.