Past: The money the family is set to receive in A Raisin in the Sun comes from the family patriarch, Big Walter, as the payment on his life insurance. This fact is significant in that Big Walter is described mainly according to his hardships and his values. The money then becomes morally charged, and it tied directly to the family's history of struggling in relative poverty.
Present: The apartment the Younger family shares is too small for their needs and has simply been worn out. Ruth refers to the apartment as a "rat-trap" and Mama reluctantly agrees. The money has the power to transform the family's life in a number of ways and leads to the conflict as to what is the best way for the family to change. The money can make Beneatha's dreams come true and send her to school. It can make Walter's dream come true and function as investment money. Or it can make Mama and Ruth's dream come true and buy the family a house.
Future: The question of the family's future for most of the play is wrapped up with the present dilemma of what to do with the life insurance money. However, at the end of the play, the money is no longer central to the family's decision. The money ultimately represents the power to make a choice and represents power more generally, but can be seen finally as only symbolic and not essential to the family's future. This conclusion, obviously, is a hard-fought one for the Younger family.