Cessnock's cast-iron structure was taken away by workmen in August, provoking a campaign on the social networking website Twitter. It won the backing of local MSP and Deputy First Minister Nicola Sturgeon.
Now Strathclyde Partnership for Transport (SPT) has returned the sign which was designed by Lachie Munro of Glasgow-based Munro Associates as the city's revival gathered steam in the 1980s.
Campaign founder Avril Williamson said: "I'm so pleased the sign has been returned to its rightful place.
"It was strange getting used to Cessnock without it there, it was like a missing tooth.
"I was amazed at the reaction to the Twitter campaign because I basically started it by tweeting about my annoyance.
"Before I knew it there were so many people getting involved. All of them, including Nicola Sturgeon, played a big part on getting the sign back."
Mr Munro who had backed calls for the arch, which were described by SPT as of no architectural significance, said: "To see it back is wonderful. I was touched by the number of people who wanted them returned."