The poem was written as a tribute to Whitman's fervor for the great Westward expansion in the United States that led to things like the California Gold Rush and exploration of the far west.
For we cannot tarry here, We must march my darlings, we must bear the brunt of danger, We the youthful sinewy races, all the rest on us depend, Pioneers!
We detachments steady throwing, Down the edges, through the passes, up the mountains steep, Conquering, holding, daring, venturing as we go the unknown ways, Pioneers!
We primeval forests felling, We the rivers stemming, vexing we and piercing deep the mines within, We the surface broad surveying, we the virgin soil upheaving, Pioneers!
Colorado men are we, From the peaks gigantic, from the great sierras and the high plateaus, From the mine and from the gully, from the hunting trail we come, Pioneers!
From Nebraska, from Arkansas, Central inland race are we, from Missouri, with the continental blood intervein'd, All the hands of comrades clasping, all the Southern, all the Northern, Pioneers!
On and on the compact ranks, With accessions ever waiting, with the places of the dead quickly fill'd, Through the battle, through defeat, moving yet and never stopping, Pioneers!
Life's involv'd and varied pageants, All the forms and shows, all the workmen at their work, All the seamen and the landsmen, all the masters with their slaves, Pioneers!
I too with my soul and body, We, a curious trio, picking, wandering on our way, Through these shores amid the shadows, with the apparitions pressing, Pioneers!
Lo, the brother orbs around, all the clustering suns and planets, All the dazzling days, all the mystic nights with dreams, Pioneers!
These are of us, they are with us, All for primal needed work, while the followers there in embryo wait behind, We to-day's procession heading, we the route for travel clearing, Pioneers!
(Shrouded bards of other lands, you may rest, you have done your work,) Soon I hear you coming warbling, soon you rise and tramp amid us, Pioneers!
Not for delectations sweet, Not the cushion and the slipper, not the peaceful and the studious, Not the riches safe and palling, not for us the tame enjoyment, Pioneers!
Whitman's poem was written as an ode to the pioneers who had set out in search of a more fulfilling life by settling in the American West.
Throughout the poem Whitman pays homage to the pioneers' courage and fearless choice to set out to find a brighter future.
The poem deals with perseverance and the enthusiasm towards exploration in America as compared to “Western youths” which refers to the young United States, and “Elder races” which refers to the European countries “shrouded bards of other lands” that once had the opportunity to explore the western territory.
In the poem the myth of the west, which was incredibly important in the bringing up of the United States, acts as a continuum linking the past to the future; showing the potential of the new America.
This is another example of how Whitman puts a strong emphasis on unity in the poem, it is not targeted towards men only, he is calling out to every individual making the migration to the west.
[4] The poem is also a representation of the revolutionary war through the description of the youthful race of America going up against the older generation in order to shape the future of the country.
By using the same allegorical metaphor to represent manifest destiny and America as a country Whitman shows that his passion for exploration wasn’t limited to what he could do by himself.
For example, the line “Down the edges, through the passes, up the mountains steep” refers to the pioneers forging the trails and often crossing difficult terrain, they had to create new lives for themselves through hard work and sacrifice, making it possible for others to follow in their footsteps.
His imagery and emotional appeal makes it possible for him to achieve the total effect of his poem and project the meaning to the reader.
Poems such as "Song of the Broad Axe", which dealt with similar themes like Americas westward expansion, and "O Captain!
Whitman made constant revisions to Leaves of Grass throughout its publications and in doing so transferred the poem to different sections in the various collections.
[12] During the 2013 NCAA Division I FBS football season The Pac-12 Conference used selections of the poem in their commercial promoting the Pac-12 Network and their schools in the Western United States.