Why did the economy of the 1920s resulted in quickly expanding prosperity for many americans, but continued poverty for others

Not all industries prospered in the Boom in the 1920s of America.

Old industries such as Coal and Cotton did terribly in the Boom as people became interested in the new products such as clothes made from artificial material(polyester). Coal was an old source of power, in the 1920s oil and electricity became greatly used.

Agriculture was also poor many farmers left the farmland to find work in the city. As new people emerged, new demands also appeared. Instead of fresh fruits and vegetables, Americans preferred cereals and bread which lead to the decrease of demands in fruits.

In the 1920s, Argentina and Canada began to supply the world crops which lead to the drops of demands from USA directly. Later in the year Prohibition(anything related to alcoholic drinks was made illegal) was introduced which caused an instant drop to the demands of barley(barley was used for making alcoholic drinks such as beer)