 Some markers also feature the small abbreviation "CORR Z" near the top of the state outline, though this practice is being phased out.All of SR 520 from the Alabama state line to at least the eastern intersection with US 17/SR 25 near Jekyll Island is part of the National Highway System (NHS), a system of routes determined to be the most important for the nation's economy, mobility and defense.The roadway that would eventually become SR 520 was established in 1920 as SR 1 from Columbus to Cusseta, SR 32 from Dawson to Sylvester, and SR 46 from Sylvester to Tifton.