I like to see it lap the Miles
Basically, there's not much "plot" in this brief, riddle-like poem. In it, Dickinson describes the progress of a strange creature (which astute readers discover is a train) winding its way through a hilly landscape. The speaker admires the train's speed and power as is goes through valleys, stops for fuel, then "steps" around some mountains. The animal-like train passes by human dwellings and, though it observes them, doesn't stop to say hello. Instead, it goes on ahead, chugging loudly as it passes through a tunnel, and steams downhill. Finally, the train (compared in the end to a powerful horse) stops right on time at the station, its "stable."