What is the fine-grained topic of the following text: Pulled from Kerouac’s diary, it traces the route of a hitchhiking trip of July through October 1948, which no doubt fueled the still-potent literary impact of his best-known book, which would see publication almost a decade later in 1947. Only return the topic.
Kerouac's 1948 hitchhiking trip and its influence on his best-known book.