Emergence of a mythic “Wild” West during the Gilded Age

What might account for the emergence of a mythic “Wild” West during the Gilded Age? Given the rapid post–Civil War expansion of

industry beyond the Mississippi River, why would perceptions of a West, at once a lawless but timeless romantic frontier dominated

by cowboys and Indians, permeate American popular culture in the late nineteenth century? (In composing your answer, consider the

impact of the second industrial revolution.)