This may come as a shock to you, but the setting for "Song of the Open Road" is… the open road. Now that you've gotten back up from falling out of your chair, it's worth saying a bit more about this place. It's only fair after all, since Whitman gives us more than 230 lines and seventeen sections about it.
What's so great about the open road? The poem puts forth a few key ideas. The first thing that makes it so great is all the people you can meet there. Walt Whitman was a people poet. He loved to celebrate every race, creed, and profession of his fellow countryman, so it's no surprise that we get a line like: "Here the profound lesson of reception, neither preference or denial" (17).
By "here," the speaker means the road, and by "reception" he's not talking about his cell phone. He means receiving other people, whom he's not going to show preference or denial. In other words, he's down to meet anyone and everyone. The road is a super-democratic place, upon which everyone must travel—poor, rich, black, white, man, woman, etc. Whitman's speaker sees this is the perfect place to embrace 'em all.
But that's not the only reason he loves him some open road. It's also a chance to break out of the daily grind of day-to-day life, to be fully free to experience life:
From this hour, freedom!
From this hour I ordain myself loos'd of limits and imaginary lines,
Going where I list, my own master, total and absolute, […]
Gently, but with undeniable will, divesting myself of the holds that would hold me. (53-58)
With these lines, Whitman helpfully explains why the road trip is such a popular backdrop for film and other works of literature. It allows folks to break free of their routines, to more fully explore all that life has to offer—even if it's just a Mountain Dew and some beef jerky at a roadside Quicky Stop.
More profoundly, though, there is a third reason why this setting is important to our speaker, and why it should be important to you:
Of the progress of the souls of men and women along the grand roads of the universe, all other progress is the needed emblem and sustenance. (189)
This line is worth unpacking just a little bit: "emblem" here means sign or symbol, while "sustenance" means nourishment. In other words, to travel down the open road prepares you for the ultimate voyage of the Soul into the Great Beyond. Our speaker admits that he doesn't know where we'll all end up after we pass from life, but he does underscore the idea that we are all of us travelers.
In short, he takes the idea that "life is a journey, not a destination" to new lengths. The open road is not just a trip for him, and it's more than just a setting for this poem. For Whitman's speaker, it's the ultimate metaphor for human existence.
How's that for a road trip?