There are numerous references to Maycomb's close-knit community, but the first, and perhaps most relevant, example can be found in chapter 1. Much of the novel's first chapter consists of a grown-up Scout's narration describing her family's heritage, and on page 5 (Everbind edition), she discusses Atticus's history in Maycomb:
Atticus derived a reasonable income from the law. He liked Maycomb, he was Maycomb County born and bred; he knew his people, they knew him, and because of Simon Finch's industry, Atticus was related by blood or marriage to nearly every family in the town.
With this quote, Harper Lee immediately establishes Atticus as a well-known and well-respected citizen--one whose integrity and opinions are recognized in Maycomb.
Further, when a group of concerned citizens shows up on the Finches' front lawn to discuss the Tom Robinson trial in chapter 15, Jem, who watches from the livingroom window, senses that Atticus is in some sort of danger. When he asks if the men were going to "get" Atticus, Atticus replies, "No son, those were our friends." With this statement, Atticus successfully turns what Jem tried to describe as a "gang" into a group of individuals the family knows.
Finally, in Chapter 16, Atticus reflects on the incident outside the jail (which occurs in Chapter 15) and insists that a mob of people, like the group that came with the intentions of hurting Tom Robinson, is nothing more than a group of individuals:
A mob's always made up of people, no matter what. Mr. Cunningham was part of a mob last night, but he was still a man. Every mob in every little Southern town is always made up of people you know--doesn't say much for then, does it?
Again, this statement reinforces Atticus's belief that individuals should all be recognized as equals, no matter what their color, gender, or social class is. The novel's small-town setting of Maycomb helps readers grasp this concept, as most all of the characters are aquainted with each other.