The first chapter of To Kill a Mockingbird tells the story of Maycomb through the eyes of Scout. This is when it is first described as "an old town, but a tired old town" when Scout first remembers it.
Scout refers to it as an "old, tired" town because Maycomb is an isolated place through which time passes without making any difference. The description that follows confirms this assumption, as it shows how the aesthetics of Maycomb present to the reader a town that is desolate, left to its own devices, and without any sign of intervention from its community members. This is indicative of a town those inhabitants are so divided that they cannot even make a collective effort to merely make their town look better, or become more productive. This leaves the reader with the impression that Maycomb is similar to a ghost town in its ongoing detriment but it is different only in that it still has residents living there.
In rainy weather the streets turned to red slop; grass grew on the sidewalks, the courthouse sagged in the square.
In towns and communities where collective pride and brotherly love exist, people get together and work toward a common goal that will benefit both their town and their community. The fact that Maycomb is so dejected makes the reader wonder whether the inner sanctum of each individual living in Maycomb is as equally devoid of self pride and purpose.
Back to Scout's account of Maycomb, she continues her description of the town explaining how the aesthetically unappealing appearance of the place is permeated by the added annoyance of a melting heat which reduces the well-dress ladies to "soft teacakes with frostings of sweat and sweet talcum".
It would seem as if the people of Maycomb have no inkling about a world that would be different from their own. They seem to allow time to pass by, and for things to "just happen". Nobody seems to question anything; notice how, even though the heat seems to destroy any attempt of beauty, the ladies continue their same practices of dress as usual. This will be an important point to ponder upon later. These are the very people that will not question the validity of the Ewell's testimony either, and who will allow Tom Robinson to go to jail unfairly.
Therefore, from that first chapter the reader can foreshadow that the inhabitants of Maycomb will act upon tragedy in the same manner in which they act in their daily lives: without changing a thing. They will continue to let things "just happen", and they will refuse to change with the passing of time. They simply will remain null and indifferent to what is obviously wrong. All these are ways to ascertain how the town is, indeed, "old and tired".