In the first chapter of Part One, Sal meets Dean and his wife, Marylou, whom he describes with imagery and similes:
Marylou was a pretty blonde with immense ringlets of hair like a sea of golden tresses; she sat there on the edge of the couch with her hands hanging in her lap and her smoky blue country eyes fixed in a wide stare because she was in an evil gray New York pad that she'd heard about back West, and waiting like a longbodied emaciated Modigliani surrealist woman in a serious room.
Kerouac first describes Marylou's hair with a simile: it is "like a sea." Golden tresses are literally descriptive of her hair (a "tress" is a lock or ringlet of hair), but the sea comparison is metaphorical. He goes on to use imagery to help the reader imagine her blank stare, which Sal attributes to her awareness of the "evil gray New York pad" that she's in. Perhaps Marylou is doubting her marriage and the place it has landed her in. "Smoky blue" suggests her eyes have a gray tint to them.
Kerouac often uses words poetically—that is to say, he picks nouns, adjectives, and verbs that don't make sense literally, but do serve a poetic function and concisely give the reader information about the scene. Marylou's "country eyes" are a good example. What would make eyes "country"? A literal interpretation doesn't make sense, but a figurative one might suggest that, because Marylou is from the country, her eyes are not accustomed to sights like New York City.
Finally, Sal uses a simile to compare Marylou to a "longbodied emaciated Modigliani surrealist woman." This is an allusion to Amedeo Modigliani, a modernist painter with connections to Cubists and Pablo Picasso.
In Part 1, Chapter 7, Sal moves in with a writer friend, and he describes the situation with two literary allusions.
The following ten days were, as W. C. Fields said, "fraught with eminent peril"—and mad. I moved in with Roland Major [...] We each had a bedroom, and there was a kitchenette with food in the icebox, and a huge living room where Major sat in his silk dressing gown composing his latest Hemingwayan short story—a choleric, red-faced, pudgy hater of everything, who could turn on the warmest and most charming smile in the world when real life confronted him sweetly in the night.
W. C. Fields, whom Kerouac alludes to multiple times in On the Road, was a writer and comedian. Fields's vibrant radio and film persona made him famous to any American with access to mass media. The second allusion in this passage is to Ernest Hemingway, a modernist author who wrote about his adventures in the States and abroad, and who (like Kerouac) drank heavily. Like his fellow Beat artists, Kerouac easily mixes high-brow and low-brow allusions and references in his work. Many of the allusions he makes in his works are to American artists such as Fields and Hemingway.
It's also worth noting the personification in the passage above: personified "real life" confronts Roland Major and turns him from a grumpy writer into someone with a charming smile. It's not obvious what this means, and a reader may come up with his or her own plausible interpretation. Perhaps Sal means that Major finds more happiness and satisfaction in the nighttime, and at these moments his "choleric" exterior fades away.
Sal is well-read, as writers tend to be, but his friends aren't all as interested in literature as he is. When they work as guards at the barracks, Remi alludes to Fyodor Dostoevsky (author of Crime and Punishment and The Brothers Karamazov, among many other novels and stories) to describe their supervisor's appearance, but is more interested in Sal's anecdotes about the Russian author than Dostoevsky's literary genius.
[Remi] asked me, "What's the name of that Russian author you're always talking about—the one who put the newspapers in his shoe and walked around in a stovepipe hat he found in a garbage pail?" This was an exaggeration of what I'd told Remi of Dostoevski. "Ah, that's it—that's it—Dostioffski."
Readers should note that there are many correct ways to spell Dostoevsky's name. Since Dostoevsky is Russian, his name is spelled in Cyrillic, a different alphabet than the one English speakers use. But while Sal's spelling of Dostoevsky is correct, Remi mispronounces the author's name, an indicator that his only exposure to Dostoevsky is through his friend Sal's humorous anecdotes. It's not clear what Remi means when he references stories about Dostoevsky putting newspaper in his shoes or wearing a secondhand top hat. However, the protagonist of Crime and Punishment wears a worn top hat, which may be the origin of the "exaggeration" Sal describes.
In Chapter 14 of Part 1, in addition to making another literary allusion, Sal builds a metaphor that compares staring out of his bus window to reading.
I had a book with me I stole from a Hollywood stall, "Le Grand Meaulnes" by Alain-Fournier, but I preferred reading the American landscape as we went along.
Sal's allusion is to French author Henri-Alban Fournier's only novel: Le Gran Meaulnes (literally The Great Meaulnes), a coming-of-age story about a teenager's obsession with a girl. The details of the novel aren't important since, as Sal says, he prefers "reading the American landscape" to reading the novel. This metaphor suggests a few things. Firstly, Sal's travelling is not simply pleasurable, but also educative. Perhaps (like reading canonical works of literature) his journeys even help him gather material, inspiration, and experiences for writing. Second, Sal's attention to the American landscape is as intelligent and focused as the act of reading.
In this formulation, both kinds of "reading"—novels and examining the landscape—are equally important for Sal's writing. Finally, note that Sal chooses the American landscape over the French novel. The detail is small, and Kerouac may not have meant anything by it, but readers may also interpret this moment as a prioritization of America over Europe, or of the new over the old.
In Chapter 4 of Part 2, Sal goes to a party thrown by a man named Rollo Greb, whom he describes with an allusion and metaphorical language.
[Greb] played Verdi operas and pantomimed them in his pajamas with a great rip down the back. He didn't give a damn about anything. He is a great scholar who goes reeling down the New York waterfront with original seventeenth-century musical manuscripts under his arm, shouting. He crawls like a big spider through the streets. His excitement blew out of his eyes in stabs of fiendish light. He rolled his neck in spastic ecstasy.
The allusion is to the operas of Giuseppe Verdi, a 19th century composer who, by Kerouac's time, would have been recognized as a great artist. By mentioning that Greb acts out Verdi's operas, Kerouac intends readers to understand that Greb is both cultured and eccentric: he doesn't just know these famous operas but loves them to the point of embarrassing himself in public in order to express his enthusiasm.
With a simile, Sal says that Greb "crawls like a big spider" in public, a brief but evocative image that allows the reader to imagine this eccentric, unkempt man slouching through Long Island. Sal metaphorically says that Greb's "excitement blew out of his eyes in stabs of fiendish light." Obviously this phrase cannot be literal, but the reader has no trouble understanding what it means: Greb's enthusiasm often seems brilliant and even violent.
In Chapter 6 of Part 2, Sal travels to New Orleans with Dean and Ed Dunkel to see his old friend, Bull Lee. Sal describes Bull with a metaphor, and he also relays a literary allusion Bull makes:
Bull called [his son, Ray] "the Little Beast," after W. C. Fields. Bull came driving into the yard and unrolled himself from the car bone by bone, and came over wearily, wearing glasses, felt hat, shabby suit, long, lean, strange, and laconic, saying, "Why, Sal, you finally got here; let's go in the house and have a drink."
Once again, Kerouac alludes to the comedian W. C. Fields, although here he places the allusion into Bull's mouth. The character of Bull Lee is based on the Beat writer William Burroughs, and Bull Lee's family in On the Road are based on Burroughs's actual family, although it's not clear whether Burroughs called his son "the Little Beast." Regardless, the allusion serves to establish a point of commonality between Bull and Sal: they both have a thorough understanding of American culture of all kinds.
Kerouac's description of Bull employs both metaphor and imagery. He metaphorically writes that Bull "[unrolls] himself from the car bone by bone," which suggests that Bull is skinny and slow-moving, just as Burroughs was in real life. Kerouac also creates a thorough image of Bull that includes what he wears and how he moves. Kerouac is a master of characterization through imagery and dialogue, and this moment is no exception.
Sal describes yet more of Dean's skilled but irresponsibly fast driving in Chapter 9 of Part 3. His description involves a simile, a metaphor, and precise verbs that allow the reader to imagine Dean's eager yet deliberate maneuvers.
Dean came up on lines of cars like the Angel of Terror. He almost rammed them along as he looked for an opening. He teased their bumpers, he eased and pushed and craned around to see the curve, then the huge car leaped to his touch and passed, and always by a hair we made it back to our side as other lines filed by in the opposite direction and I shuddered. I couldn't take it any more.
The Angel of Terror is the title of a 1922 mystery novel by Edgar Wallace, a prolific British writer whom Kerouac may well have read. Sal might be alluding to that book here, or possibly he's just using the phrase to suggest that the drivers whom Dean tailgates are terrified. After the "Angel of Terror" simile, Sal personifies the car as if it is a responsive horse or even an extension of Dean's body. The car "leaped to [Dean's] touch" in order to pass on the single-lane highway, a dangerous maneuver. Sal idiomatically says their car passed without getting into a wreck "by a hair," by which he means they barely made it.
In Chapter 11 of Part 3, Sal's descriptions of his travels become melancholy. This tone is communicated with a simile in which Sal compares himself to a traveling salesman who sells something no one wants to buy.
In the misty night we crossed Toledo and went onward across old Ohio. I realized I was beginning to cross and recross towns in America as though I were a traveling salesman—raggedy travelings, bad stock, rotten beans in the bottom of my bag of tricks, nobody buying.
First, note the alliteration in the phrase "old Ohio." After his usual brief descriptions of the places he crosses through, Sal reflects with some displeasure that he's only retreading the same ground as before. In a simile, he compares himself to a traveling salesman, and not a successful one: he says the kind of salesman he's similar to is "raggedy," with "bad stock" that won't sell. The "rotten beans" comment may be an allusion to the story of Jack and the Beanstalk, in which Jack buys magic beans that his mother thinks are a hoax. What is Sal selling, and why isn't anyone interested? Perhaps he worries in this passage that his attempts to find purpose and spiritual meaning are pointless "tricks" that are obviously rotten to everyone but him.
In Chapter 6 of Part 4, Sal drives through Mexico as his friends sleep. He sees shepherds and describes them with imagery and a biblical allusion:
The shepherds appeared, dressed as in first times, in long flowing robes, the women carrying golden bundles of flax, the men staves. Under great trees on the shimmering desert the shepherds sat and convened, and the sheep moiled in the sun and raised dust beyond. "Man, man," I yelled to Dean, "wake up and see the shepherds, wake up and see the golden world that Jesus came from, with your own eyes you can tell!"
Recall that On the Road is, according to Kerouac, about a spiritual quest for meaning as much as it is a series of physical journeys. Fittingly, in one of the final chapters of the novel Sal sees a biblical scene: shepherds. Shepherds have a crucial place in the Bible's New Testament, both as actual people (such as when shepherds visit the newborn Jesus) and as a symbol of Jesus's guidance of humankind. Accordingly, Sal sees these Mexican shepherds working in rustic, pre-industrial conditions, and he feels as if they are a part of the "golden world that Jesus came from," a world of poverty and labor.
Kerouac takes great care to describe this biblical scene with imagery. The shepherds are dressed in "long flowing robes" and carry crops and staves. Because of the heat, the desert is "shimmering," and the sheep kick up dust. The passage is full of light: twice Kerouac uses the word "golden," and both the sunshine and the heat are mentioned.