Answer :
The growth was due to the indeustrial revolution; the invention of many different things. Such as the development and improvment of the assembly line and factories. Though this contributed to poor living conditions. Better living conditions would not arise till pre-world war two. But the devlopment of the middle class came about (before it was lower and high, no middle). Other inventions that helped with production, farming, and things like that would help life in America progress. But since living conditions were bad; there is more darkness till the light.