What kind of writing style is " I hear America singing " by Walt Whitman

This is a poem that is written in free verse using many metaphors (comparing two unlike things without using like or as). Free verse means it is free of limitations of a regular meter or rhythm, and does not rhyme with other words in a set line to line format. An example of a metaphor: The sun was a smiling face bringing cheer to the world. The sun is being compared to a smiling face.