Conversation so far:
Is Leaves of Grass by Walt Whitman a poem?
Leaves of Grass is a poetry collection by the American poet Walt Whitman.
When did Walt Whitman first writing Leaves of Grass?
As early as 1850, Walt Whitman began writing what would become Leaves of Grass.
What are some of the subject matters of Leaves of Grass by Walt Whitman?
Walt Whitman intended to write a distinctly American epic and used free verse with a cadence based on the Bible with Leaves of Grass.
How long or how many poems are there in Leaves of Grass by Walt Whitman?
By the time the last edition was completed, Leaves of Grass by Walt Whitman had grown from a book of 12 poems to a hefty tome of almost 400 poems.

Question: When was it published?
Self-contained rewrite: When was Leaves of Grass by Walt Whitman published?