The setting in this powerful play is so important as it evokes the kind of claustraphobia and lack of opportunities that are plaguing the Younger family. Remember the key focus of the play from the very beginning is the way that Mama and Ruth primarily want to move from their current abode and to buy a house where they can all have more space to live, breathe and dream. Note how this is shown to be impossible by the stage directions that are given at the very beginning of the play:
The YOUNGER living room would be a comfortable and well-ordered room if it were not for a number of indestructible contradictions to this state of being. Its furnishings are typical and undistinguished and their primary feature now is that they have clearly had to accommodate the living of too many people for too many years--and they are tired.
The adjective used to describe the furnishings, "tired," also describes the Younger family, and note too how the description continues saying that various furnishings have to "fight" to be seen, perfectly capturing the crowded atmosphere in which the Younger family are struggling to survive and to develop. The setting acts as a powerful symbol of not only the physical limitations that impinge on the Youngers, but also the more powerful exterior limitations that prevent them following their dreams: racism, poverty and discrimination.