moving (line 7)
Perhaps no other word could capture the American metropolis better than this one. The word "moving" occurs right in the middle of the poem – it is central to the image of modern life that Williams presents. Like the fire truck, Americans are in a state of hectic tension.
and wheels rumbling through the dark city (lines 12-13)
The city feels rather big and anonymous at the end of the poem. The wheels' echo rumbles through the streets like an unnatural storm. Is the word "dark" meant to be negative?