People used the information sources that the Internet replaced. Cities had daily papers - often more than one - with huge thick classified ads sections -- filled with little ads placed by individuals for a few dollars -- that were updated every day. Then there were neighborhood and special interest weeklies, with their own classified ads. The income from all those ads supported more papers, each with more writing on local events. There were magazines and newsletters on all kinds of esoteric topics. And bulletin boards at cafes and shops. Libraries had the newspapers and phone books of other cities, and some of the magazines and newsletters. Radio stations, too, had announcements of local events.
And you would have a network of friends and relatives and acquaintances, and visitors to all of them passing through. You would call them on the telephone and write letters. Many would respond promptly because they, too, wanted to stay in touch.