Jack Kerouac's On the Road is the defining work of the Beat Generation, a youth subculture of the 1940s and '50s that rejected the conformism of its time. It is a book of ideas and characters more than plot, and through the journeys of the main characters, the reader sees a picture of rebellious American youth and their attempts to subvert the cultural mandates they had been given in order to conform to white middle-class life. Kerouac's prose emulates jazz and the energy of the time. The book documents the four cross-country journeys of two friends, Sal Paradise and Dean Moriarty--the fictional alter-egos of Kerouac and the Beat writer Neil Cassady--and their cast of friends, acquaintances, wives, and lovers.
The book begins with Sal relating how he came to know Dean. Dean had been released from a reform school prison and had come to New York to take part in its artistic and intellectual scene. Sal is enamored with Dean; he is a frenetic madman with a lust for alcohol, drugs, and women that is equally matched by his lust for living. Dean's energy sets off Sal's own desires for adventure and exploration, so after Dean returns to his hometown of Denver, Sal decides to set out on his own journey to meet up with his friends. Sal hitchhikes and takes buses to Denver, meeting an array of different characters. Many of these people are travelers as well, people who live in the impoverished and ever-moving world of hobos and hitchhikers.
Dean takes in the American landscape and the American West. In Denver he meets up with Dean and several other friends, and they spend their time partying, drinking, and doing drugs. As his time in Denver draws to a close, Sal departs for San Francisco to live for a while with his old friend Remi Boncoeur. Sal works a job as a security officer until his relationship with Remi deteriorates and he leaves San Francisco. On his way back to New York, he meets a Chicano farm girl, Terry, and they work in the cotton fields of California together for several months. Sal thinks he is in love and enjoys becoming a part of this marginalized culture, but the cold weather of winter eventually drives him back to his life in New York.
Sal's second journey begins as Dean drives from San Francisco to Virginia to pick him up at his family's house over Christmas. Driving Dean's Hudson car, they drive to New Orleans to visit Old Bull Lee, a mentor and drug addict who was taking care of the wife of one of Sal's and Dean's friends. They had abandoned the woman in a hotel on their way to Virginia, but she had sought them out through Bull Lee. The group drive through Texas and Arizona, stealing gasoline and food as they need it, until they finally reach San Francisco. Dean abandons Sal and his ex-wife Marylou in San Francisco to live with his current wife, Camille. Dean and Sal eventually meet back up, getting their "kicks" in San Francisco, visiting the African American jazz clubs, and drinking until dawn. Eventually Sal, wearied and broke from his travels, returns to New York.
The third journey begins with Sal in Denver. He has come to start a new life, but he finds that he is lonely and bored since none of his friends is there. He longs to be a part of the marginalized cultures he sees in Denver, to take part in the freedom that he believes their poverty and social status give them. Sal then decides to go to San Francisco to meet up with Dean and the rest of the gang. Dean had been trying to start a new, more domestic, life as well, but as soon as Sal arrives Dean's madness returns. Dean's wife Camille kicks him out of the house, frustrated with his lack of responsibility for his children and family. Sal and Dean embark on another journey, this time declaring they will go to Italy. Their journey begins in San Francisco with a night of partying and jazz clubs with their old friends. They then catch a ride with a gay man from whom Dean tries to swindle money, and eventually they end up in Denver. In Denver, Dean's lust for young girls almost gets him shot, and the two spend a wild evening at clubs, doing drugs and getting drunk, and Dean begins stealing cars. He steals the wrong car, however, the car of a police detective, and they decide they need to get out of Denver fast. They find a man who wants them to drive his Cadillac to Chicago for him, and they eagerly jump at the chance. Dean drives the car wildly through the Midwest, often at over one hundred miles per hour, and they drive from Denver to Chicago in seventeen hours, an amazing and reckless time for pre-interstate America. In Chicago, Dean and Sal again party and visit the jazz clubs of the town before catching a ride to New York. In New York, Dean meets another girl at a party, Inez, and she becomes pregnant by him. Their trip to Italy never happens.
The fourth and final journey is not a trip West but a trip South. Sal sets out on his own this time to see Mexico, leaving Dean and Inez in New York. But Dean catches Sal in Denver and, with a friend named Stan Shephard, they take off for Mexico together in an old Chevy car that Dean bought with the last of his savings, abandoning his new child and lover in New York. Dean's alibi is that he wants a cheap Mexican divorce from his second wife, Camille. They drive through Texas and cross the Mexican border. They are enthralled by the culture and freedom that Mexico offers. They are set on getting to Mexico City, but along the way they stop in several small towns. In one, they meet a guide, Victor, who gives them drugs and takes them to a whorehouse where they have sexual encounters with underage girls, all for very little money. The police do not care, and the culture gives them the freedom that they had always desired in America. In the mountains of Mexico, they encounter the natives of the land and marvel at their impoverished and simple way of life. In Mexico City they find what might have been a kind of Beat haven, but Sal gets sick with dysentery, and Dean leaves him there. When Sal is well enough, he leaves Mexico City and returns to New York where he finds that Dean, having married Inez, has left her and the child to return to his second wife Camille in San Francisco.
The book ends with Dean traveling to New York to see Sal and Sal's new partner. Sal, despairing over the mess and trouble that such a mad and free lifestyle of travel has brought him, nonetheless remains inspired by Dean's madness. This time, however, he cannot follow Dean back to San Francisco. It is the last time that Sal ever sees Dean. As the novel closes, Sal sits by the bank of a river, thinking of the great American landscape that he has seen in his journeys, and thinking of Dean.