Carl Sandburg’s “Subway” pictures a dark underground world where working people are worn down by necessity. The “walls of shadow” and “iron laws” suggest a place ruled by rigid schedules, machinery, and economic pressure rather than human warmth. In that setting, “hunger voices mock” — need and poverty are constant, taunting reminders of why these men endure such conditions.
The men themselves appear weary, with “hunched and humble shoulders,” yet they “throw their laughter into toil.” That line can feel both sad and stubborn: their joy is spent on labor, almost consumed by it, but the act of throwing laughter also hints at endurance. The speaker’s tone is somber and sympathetic, creating a mood that is heavy, gray, and oppressive, but not entirely without a trace of human struggle.