Under thy shadow by the piers I waited; Only in darkness is thy shadow clear.
The speaker's location is finally revealed: he is looking at the bridge from the piers in Manhattan.
This is the second time that "I" is used in the poem.
The speaker is waiting for something: but what?
Many readers think that waiting by the piers might be another reference to Crane's homosexuality: he is at a cruising, or pick-up spot, waiting for a man to approach him. But that's certainly not the only way to interpret this line.
Yet another of the poem's paradoxes: the bridge's shadow is most "clear" at night.
Usually shadows are made by the sun, but here the shadow is presumably made by the lights of the city.
Of course, light and shadow are loaded with symbolism, but we're just trying to keep it simple here.
The City's fiery parcels all undone, Already snow submerges an iron year . . .
The lights of the city's buildings have gone out, and it's mid-winter.
A "parcel" is a package, so a parcel "undone" is an opened package.
But a "parcel" is also a part of something (as in the phrase "part and parcel"), like the rectangular window of a rectangular building.
All the little rectangles of light in the buildings have gone out – "come undone" – leaving darkness.
The city is under a layer of snow, and maybe it's snowing right now.
The snow has "submerged" an iron year, meaning that the snows are a sign of another year passing.
Crane wants us to know that the poem is set in winter, most likely either December or January, the months closest to the new year.