What was the economy of the US during the time To Kill a Mockingbird is set?
The story takes place during the Great Depression, which was also a time of severe racial discrimination in the South.
Scout comments on the fact that almost everyone is poor when she describes the town of Maycomb.
There was no hurry, for there was nowhere to go, nothing to buy and no money to buy it with, nothing to see outside the boundaries of Maycomb County. (ch 1)
Atticus explains that the professional people are poor because the farmers are poor. The farmers have to pay them in chickens and other farm goods, rather than money. It is hard times for everyone.
Scout also establishes the setting by describing the First Inaugural Address of President FDR, who made a famous speech.
But it was a time of vague optimism for some of the people: Maycomb County had recently been told that it had nothing to fear but fear itself. (ch 1)
People have high hopes for the economy getting better, but no one thinks anything of the terrible racism that runs rampant. It is simply the way thing are. Jim Crow laws established that black Americans had fewer rights than whites. No blacks served on juries, and they were discriminated against at every turn.
Because this book takes place in the 1930's, we know that the US is unfortunately in the Great Depression. As mentioned in the above answer before me, that means many people are either poor or unemployed, with little ability to spend money. The economy is at its worst it's ever been, with unemployment high and wages low, and consumer confidence has decreased significantly. Thus, we are able to understand why Scout describes her point of view in such a poverty driven perspective.