Early GA 315 was quite short. Commissioned in 1959 fully paved, the original highway basically served as a Harris County connector from U.S. 27 in Cataula to GA 85 in Ellerslie. Extending 5.1 miles originally, the road was two directional changes as it follows pieces of previously county-maintained roads.

1961 saw GA 315 extended to a highway nearly four times longer than the original route. Extending east of Ellerslie, the extension was completely unpaved, unlike the original route. Named Ellerslie-Talbotton Road, the extension included an 0.5 mile overlap with GA 85 and a 12.2 new section that took the highway into Talbot County ending at GA 208. Parts of the road that would become the western extension of the highway also appeared on the map that year as well.

In 1964, paving of GA 315 was completed, but no further action was taken on the highway for several more years. The final section of GA 315 was commissioned in 1971, extending the highway west of U.S. 27 to GA 219 (River Road). The addition of this final segment appears to have coincided to when I-185 was first proposed. The extended GA 315 indeed later had an interchange built for it, and ultimately serves the Mulberry Grove community.

Like the other sections, the western segment of GA 315 was created out of multiple county roads, and a very short overlap with U.S. 27 was included in the extension. The last extension has no less than three directional changes with existing county roads, and was nearly as long as the second extension at 12.1 miles. In 1980, the interchange with I-185 opened, connecting rural GA 315 to the interstate highway system and was the final major change to GA 315.