The poem takes us to the land where the sidewalk ends with a pace that is measured and slow (yeah, we stole that, we know), but we can't help but feel a little bounce in the poem's step. There is so much to notice when it comes to sounds in this poem that it would be easy to get lost. Luckily Shmoop's here to draw some chalk-white arrows for you, and our arrows all point to – you guessed it – alliteration.
Alliteration abounds as the poem bounces from sound to sound. On one line "b" sounds surround, and on the next, "p" is all around. There are "g's" and "w's," too. That's all well and good, but what's the point?
When you read this poem aloud, you can't help but notice that the alliteration adds a sense of fun and whimsy. It gives the lines a bouncing joy that jumps right off the page and into your ears. It makes lines more memorable, and adds emphasis in key places.
Consider the contrast between the alliterative "grass grows" (3) and "blows black" (7). In both cases, the alliteration helps highlight the qualities of what's being described. We know that the place where the sidewalk ends is awesome, because the grass grows there. It's a pleasant phrase, which makes it all the more unpleasant that smoke blows black in the place with sidewalks.
Silverstein is a master at playing with sounds this way, which is perhaps why his poems are so popular and memorable. He mixes unforgettable ideas and images with sounds that stick in your brain, which makes all those awesome ideas stick, too.
When you read this poem (and please, do so out loud!), imagine it drifting along on a peppermint wind. Memorize it to amuse on command, and shout it out when the real world has got you down. But most of all, just have fun with the sounds of this poem. Because fun is what it's all about.