The A764 was a short spur in the Rhins of Galloway.
Starting on the A77 to the east of Portpatrick, the road headed north through the undulating, sparsely populated countryside, passing the occasional farmstead but nothing even as large as a hamlet. After passing Portslogan, the road ended at the fork, with the B738 continuing ahead and an unclassified road along Glenstockadale heading right.
Originally numbered as part of the B738, the A764 was created in the late 1920s for no apparent reason as it served no places of any note. It is not surprising that it has now reverted to its original number; what is surprising is that it remained the A764 until at least the 1970s.