The train is a symbol of technological advancement. Its comparison to a horse makes technology seem friendly and familiar—like another strong tamed animal—but Dickinson regularly undercuts the quaint depiction. Like the train, technology is voracious. It collapses distances and fits into a variety of spaces. Technology also threatens nature, upsetting the natural order by being “prompter than a Star” (Line 15), producing “horrid—hooting” (Line 12), and forcing mountains to be shaved into quarries for its passage. 

The progress of technology does not benefit all equally. The presence of “Shanties” (Line 7) hints at the fates of the people responsible for keeping the train on its rail—they live in sad shacks by the side of the tracks, exposed to the noise and disruption the train brings. In contrast, those who own this technology evade responsibility for their inventions by presenting technology as autonomous—the speaker is delighted to image the train as “docile and omnipotent” (Line 16) creature, one of bridled power.

The small, vulnerable houses the train passes by symbolize socioeconomic inequity. After traversing the mountains, the train takes a “supercilious peer / In Shanties—by the sides of Roads” (Lines 6-7). The image juxtaposes the wealth this technological achievement brings to the robber barons who control it with the poverty of the shanties’ residents, who are responsible for the actual existence of the tracks the train traverses.