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.
A cancellation took place on March 16, 1937, for a section from Hubbard to Munger due to another task. This section was reinserted on October 24, 1938. On October 25, 1938, SH 171 was extended southeast to Mexia along the old route of US 84/SH 7.