The correct answer to this open question is the following.
The parameters of this unit are the benefits of the industry as an economic trigger in the country and the many improvements in economics and US politics. It goes from the importance of the construction of more and better railroads that connected the nation, to the key industries such as the oil industry or the steel industry that modernized America.
The major turning points of this era were the benefits and challenges of industrialization, immigrant workers that arrived in the United States, reformers, labor unions and benefits for American workers, new farmer organizations that supported agriculture workers, and a middle class that increased in time and influenced the life of America.