In the years before and during the civil war, the nation’s mastery of technology had opened up vast new possibilities for material success. These possibilities became real and America became an industrious giant, which spurred many jobs for the lower classes of Americans. Although the middle-class American in the decades after civil war enjoyed the benefits of increase production, new consumer goods, and a greater standard of living, but the industrial workers lacked a decent standard of life because of the government, technological changes immigrants, and labor unions of that time period.
Laissez-Faire, the idea of the government being foreign to regulating the economy of the 19th century, allowed the industrial advances that tortured industrial workers. The big corporate owners that gave bare wages to their employees used many abusive methods to obtain the largest amount of profits. The assembly line created from technological advances caused workers to be constantly active that endanger their overall health. In the mining industry workers, which many were small children, were exposed to hazardous environments causing health issues. The invention of the Bessemer process gave rise to the steel common need for workers, but they were in constant danger from not having any of the protective accessories for the dangerous creation of steel. All these occurrences could have been stopped by the government, but were left to the common industrial worker to face.

I would greatly appreciate any comment!

Looks like you have a good start.

One thing to keep in mind with the second paragraph is that industrialization, though a terrible ordeal for the average worker, was the only way that America grew into such a powerful nation. Science and engineering advances were making all these incredible new things possible, and it would be one-sided to ignore that. So while yes, it is extremely important to point out how badly workers were abused, I think it would strengthen your essay by balancing that point with some information discussing the GOOD things of industrialization.

Also there are a few grammatical and punctuation errors, so be sure to check that as well. But yeah, I think you're definitely on the right track. :)