Maycomb’s social hierarchy is very distinct and easy to determine. At the top of the social ladder are the educated, land-owning whites, like Atticus Finch. In a small town in the Deep South, owning land gives a person or family prestige and respect. The next step down on the social ladder would be the hard-working whites, the farmers, like Walter Cunningham. Here it is obvious that hard work is what is rewarded, not the amount of money one had. Walter Cunningham has very little money but works hard to maintain his dignity and will not take charity from anyone. The next step down the social ladder is the non-working whites like the Ewells. The last and lowest rung of the social ladder is where all the African-Americans in Maycomb were. No matter the education, wealth, or land-owning status, this was their place in society. It is this discrepancy and disgrace that Harper Lee highlights in the novel. She questions a society where someone like Bob Ewell could rank higher in society than Calpurnia or Tom Robinson.
Jem explains the social hierarchy of Maycomb to Scout in Chapter 23 of To Kill a Mockingbird. After Aunt Alexandra firmly informs Scout that she cannot bring Walter Cunningham home after school to stay the night because the boy is "trash," Scout is deeply disturbed. Jem tries to explain the situation to her:
There’s four kinds of folks in the world. There’s the ordinary kind like us and the neighbors, there’s the kind like the Cunninghams out in the woods, the kind like the Ewells down at the dump, and the Negroes.
Jem elaborates that one kind of people also dislikes another kind of people; for example, people from Atticus' family don't respect the Cunninghams due to their lack of interest in education and the fact that they are "yappy" folks who "like fiddlin' and things like that." In turn, the Cunninghams despise the Ewells for their dependence on government assistance and refusal to live off the land or do hard work. The Ewells hate the black people of Maycomb, discriminating against them only because of the color of their skin. This system, although deeply prejudiced and unfair, has become an integral part of maintaining the socioeconomic status quo of this little Southern town.
This is a good question. There is no one place where a hierarchy is given. However, if we piece things together we can come to a few educated conclusions.
First, Atticus and his family are pretty high up on the social hierarchy. Scout on several occasions talks about their family's heritage in Maycomb. Also Atticus is a lawyer and Jack, his brother, is a doctor. Also Alexandra is akin to a socialite.
Second, there are others in the town like Heck Tate and Ms. Maudie. They are the average citizens of the town. They are white and solidly middle class.
Third, you also have poorer citizens, like the Cunninghams. We know that they are poor because Walter did not have food or money for food at school. Scout says that they just get by. Also Walter's father does not pay Atticus for his legal services in money but in nuts and other food stuff.
Below the Cunninghams you have the really poor - Bob Ewell and his family. The town lets them do whatever they want, like hunt off season, because they feel sorry for him.
Finally, you have the blacks. They are generally taken advantage of. This is why Tom was accused of a crime, even though he was innocent.