This question might be the kind you ask yourself when you're trying to think of content to include in an essay about the book. The interesting thing is that there are hundreds of ways you can answer this question! I'll offer a bunch, but there's no way I can cover every possible answer. Any connection that you come up with that strikes you as very meaningful or interesting, though, is a good one to use in an essay.
How does Paper Towns connect to other works of literature?
First of all, the story itself makes reference to two very important pieces of literature.
Quentin, the main character, struggles to understand Walt Whitman's poetry in Leaves of Grass. Through forcing himself to read entire long poems and through thinking about what they mean, Quentin comes to a better understanding of himself, of Margo, and of how people relate to each other (and fail to relate to each other).
Even more interestingly, Quentin was supposed to read Moby-Dick by Herman Melville and write a paper about it for English class to argue whether the main character was a hero or a fool for spending his life chasing after a whale. Quentin doesn't even read the book. He just gets the basic storyline from class discussions and decides to argue that the main character is a hero. Of course he does. Quentin himself is just like Ahab from the story, chasing after something in endless desperation. The difference is that Ahab chases after a white whale who took Ahab's leg, and Quentin is chasing after a beautiful girl who took his heart.
So, on one level, Paper Towns connects very directly to Leaves of Grass as well as Moby-Dick.
On another level, you can connect this novel in meaningful ways to others that share its general themes. What else have you read that includes someone running away in desperate search of freedom? (How about the novel The Thief Lord?) Or that includes someone who hopelessly loves someone who doesn't return that love? (How about the poem "Neutral Tones"?) Or that includes discovering a new way of thinking about human relationships? (How about the novel Firegirl?) You can keep going, of course, finding issues and conflicts in the story that remind you of others you have read.
Next, how does Paper Towns connect to history?
This is a little harder. It's a modern novel; it was published in 2008 and seems to take place in about that year as well. The only time that the characters in the story even seem to make reference to large-scale current events or to history is when Quentin listens to his parents vehemently discuss the state of politics in the Middle East.
You might argue that technology plays a major role in the plot of Paper Towns, and that, if the story were to take place in another time, it would be vastly different. The use of immediate communication devices (IMs and cell phones) makes the story possible, as do several features of the Internet: the Wikipedia-like site called the "Omnictionary," and the online maps that allow for quick distance calculations and accurate directions (as well as information about where certain gas stations will be along with highway).
The social expectations that underlie the story of Paper Towns are also firmly rooted in modern history. Everyone expects Margo to go to college and get a good job, for example. She practically cracks under this pressure and under the utter banality of those expectations. But her situation could only occur in modern times, and so you can draw a connection to history in that, even only thirty or forty years prior to this story, a typical teenage girl would have been expected to have a much different life after graduating from high school.