In 1500 AD, people living in North America spoke many different languages, and none of them were written down. Many of these languages died out in the 1500s and 1600s AD, because so many people had died of smallpox and measles that hardly anyone was left to speak those languages anymore.
In the course of the 1700s and 1800s, Christian missionaries came to North America from Europe to try to get people in North America to become Christians. Some of these missionaries tried to get people to learn English or French so that they could read the Bible. Other missionaries thought it was better to learn the local language and translate the Bible into that language.
But to translate the Bible, you had to be able to write in that language, so some missionaries designed alphabets for the North American languages. Some of these alphabets became very popular, because now people could write down their own stories and write letters to each other. One example is the Cherokee syllabary which was probably created by a Cherokee man named Sequoyah (though some people disagree).
Also during the 1700s and 1800s, there was a lot of arguing about what languages most people would speak in North America, now that all these new people were coming from all over the world. Many people in the southern part of North America spoke Spanish, and along the Mississippi valley and in Canada many people spoke French. Enslaved African people in the South spoke a variety of African languages. In the center of the continent, many Germans and Scandinavians had settled, and in some towns most people spoke German or Swedish or Norweigian. On the East Coast, most people spoke English, though by the 1750s enough of them spoke German that many English-speakers were worried about it.
When men like Thomas Jefferson and Benjamin Franklin were writing the Constitution of the United States in the late 1700s AD, they did not include any rules about an official language, but decided to leave that freedom, like many others, open for people to decide for themselves.
Nevertheless, most of the literature written in North America has been in English, which has been the language of most people living in North America since at least 1800. The earliest North American literature was mainly sermons by men like Cotton Mather, written in the 1600s and 1700s. African-American people who had come over from Africa as slaves met local Cherokee people and translated traditional African and Cherokee stories into English as the Br'er Rabbit stories. Both African-Americans like Phillis Wheatley and white people like Anne Bradstreet wrote poetry.
By the 1800s, people were beginning to write novels, or fictional stories, like those of James Fenimore Cooper (The Last of the Mohicans, 1826). A lot of people thought it was wrong to read novels, which would rot your brain and teach you bad things (like what people say about television or the Internet today). Novels began to take more serious themes, like Melville's Moby Dick (1851) and Harriet Beecher Stowe's Uncle Tom's Cabin (1852) about slavery. Soon people were also writing books especially for kids, like the Horatio Alger stories (1867), or Mark Twain's Tom Sawyer (1876), L. Frank Baum's The Wizard of Oz (1900), Lucy Montgomery's Anne of Green Gables (1906), or Frances Hodgson Burnett's The Secret Garden (1909).
In the 1900s, the use of oil in all aspects of farm work meant that most people didn't have to work on farms. For the first time in history, most kids had time to go to school and learn to read. To supply these people's reading habits, many more people in North America wrote English novels. A lot of writers lived in the South, like Eudora Welty, Thomas Wolfe, or William Faulkner. The end of slavery after the Civil War and the civil rights movement meant that more books could be written by people who were not white, like Richard Wright's Native Son (1940), Toni Morrison's Beloved (1987), and Amy Tan's The Joy Luck Club (1989). By the end of the 1900s, the Internet meant that writing was beginning to take many new forms (blogs, for instance), and many more people were able to participate in writing, as well as reading, literature. Most of this writing is being done in English, but Spanish is commonly spoken in the United States, a lot of people speak and write in French in Canada and in Louisiana, and people across North America are working to make sure their children speak and write the old languages like Cree and Cherokee.