Interstate 516 (I-516, also known as the W.F. Lynes Parkway) is a auxiliary Interstate Highway mostly in the coastal city of Savannah, located in the east-central portion of the U.S. state of Georgia. It is the only auxiliary route of I-16. For its entire length, I-516 is concurrent with State Route 21 (SR 21), which I-516 superseded in 1985. It was formerly also signed as State Route 26 Loop (SR 26 Loop). The highway also carries unsigned State Route 421 (SR 421) to ensure that all Interstates in Georgia had 400-series reference numbers. Route description 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 U.S. Route 80 (US 80)/SR 26. 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. I-516 is one of a small handful of Interstate Highways that is not a freeway for its entire length. The southeasternmost downgrades to an expressway with a speed limit, an at-grade intersection at Mildred Street,