One place to start is in 1855 with "The Lackawanna Valley" by George Inness. The painting, now in the National Gallery, was commissioned by the Delaware, Lackawanna and Western Railroad and depicts the company's first roundhouse at Scranton, and integrates technology and wilderness within an observed landscape. As his career progressed, Inness would not continue to depict a landscape blended with industry.



Some of the best images of industrial America can be found in the work of Aaron Henry Gorson, who painted Pittsburgh's steel mills. Gorson seems unmotivated by the politics that often invade art, the sense of progress, environmental damage or workers rights. When you look at his work, you don't see a march of progress, rather an attempt to see industry for what it was physically. Gorson finds the beauty in industry and captures it. The smoke, the colors, the reflections in the water-Gorson seems to look at it all as if it were a tree or sunset. Gorson's work was commissioned, however, by Andrew Carnegie, Mrs. W. S. King, the wife of a glass manufacturer; the Mellon family; and Charles Schwab. Like many of his benefactors, Gorson later moved to New York and began painting scenes of the city and views of the Hudson River, but continued to create works showing the steel mills of Pittsburgh.
Most associated with industrial art today is Charles Sheeler. I found it amusing that a web site about "Objectivist Art" listed Sheeler as an Objectivist artist. Objectivism is the philosophy of writer Ayn Rand. I felt like emailing the creators of the site this quote I located by Sheeler.

"I find myself unable to believe in Progress--Change, yes. Greater refinements in the methods of destroying Life are the antithesis of Progress. Where is the increase in spirituality to be found?"
I'm in my infancy in regards to my knowledge about Sheeler, but it would seem he is more likely being critical of the depersonalization of industry, or just depicting the way in which we can see the world around us.
Sheeler was also commissioned, by Ford Motor Company to photograph and make paintings of their factories and by Fortune magazine to "reflect life through forms…" that "trace the firm pattern of the human mind." Sheelers paintings were based on photographs, and so even the more personal painting had its origins in the mechanical photograph. I don't know for sure if Sheeler, known as a precisionist and modernist, was criticizing the loss of humanity in the modern world. To me there's elements of both admiration from the shape and form of architecture and machinery, and some sense of loss. However, when he painted the barns in Doylestown, the technique is no different. We may, on the other hand, be thinking too much about it.
"To a man who knows nothing, Mountains are Mountains, Waters are Waters, and Trees are Trees," Sheeler wrote. "But when he has studied and knows a little, Mountains are no longer Mountains, Waters are no longer Waters, and Trees are no longer Trees. But when he has thoroughly understood, Mountains are again Mountains, Waters are again Waters, and Trees are Trees."