I-516 begins in the northeastern part of Garden City, as a freeway continuation of SR 21 (Augusta Road), with which I-516 travels concurrently for its entire length. The two highways travel to the southeast to an interchange with SR 25/SR 26 Connector (Burnsed Blvd), which leads to US 80/SR 26. However, only US 80 is signed at this exit. At this interchange, SR 25 joins the concurrency. In the midst of this interchange is a crossing over the Dundee Canal. The three highways pass just southwest of the Mary Calder Golf Club. After beginning a curve to the south-southwest is an interchange with SR 25 Connector (West Bay Street). Here, US 80 and SR 26 join the concurrency. The five highways cross over the Savannah–Ogeechee Canal. A short distance later is an incomplete interchange with West Gwinnett Street. Almost immediately is an interchange with I-16/US 17 (Jim Gillis Historic Savannah Parkway). At this point, US 17 joins the concurrency. A short distance later is an incomplete interchange with Tremont Road. At Ogeechee Road, US 17/SR 25 depart the concurrency to the southwest, while US 80/SR 26 depart to the northeast. I-516/SR 21 continue to the south-southwest and have an interchange with the northern terminus of Veterans Parkway, just before curving to the east-southeast. They cross underneath, but do not have an interchange with, Liberty Parkway. They cross over some CSX Transportation railroad lines just before crossing over the Springfield Canal. Just west-northwest of Mildred Street, the freeway ends and the two highways continue to an intersection with Montgomery Street. At this point, I-516 meets its eastern terminus, while SR 21 (DeRenne Avenue) continues to the east-southeast.