"Chicago" is a poem in which the speaker looks at the city of Chicago in two very different ways. On the one hand, the city is seen as a place of prostitution where children are allowed to starve and killers are set free to kill again. On the other hand, the speaker cannot but help be impressed by the hard work and effort that has gone into the making of this city and the industrious nature that characterises it. The literary devices that are used in this poem help to support such understandings. Consider the following example:
Fierce as a dog with tongue lapping for action, cunning
as a savage pitted against the wilderness...
The two similes here both are used to describe the city of Chicago and the kind of people who inhabit it and have made it what it is. The speaker suggests that to get ahead in this kind of world you have to be both "fierce" and "cunning," and his admiration for the workers of Chicago and the city's spirit in this regard is evident.
Note how Sandburg personifies the spirit of Chicago in his picture of a young man who is located:
Under the terrible burden of destiny laughing as a young
Laughing even as an ignorant fighter laughs who has
never lost a battle...
The defiance of the city is expressed in its personification as a "young man" laughing, even though he is "under the terrible burden of destiny." In the face of crushing forces that seem to oppose it the city shows considerable spirit and bravery which make it, for Sandburg, remarkable and worthy of praise.