monthly magazine published in New York City, one of the oldest literary and opinion journals in the United States. It was founded in 1850 as Harper's New Monthly Magazine, a literary journal, by the printing and publishing firm of the Harper Brothers. Noted in its early years for its serialization of great English novels and for the fine quality of its own essays and other literature of the period, Harper's was the first U.S. magazine to introduce the extensive use of woodcut illustrations. It was a leader in publishing the writings of the most illustrious British and American authors, and by 1865 it had become the most successful periodical in the United States.

During the Civil War Harper's Monthly and its sister publication, Harper's Weekly, introduced fine drawings based on photographs by Mathew Brady (Brady, Mathew B.) and others. Its war reporting and illustrations have become a permanent and readable record of the Civil War. In the 1870s Harper's Weekly provided a forum for Thomas Nast (Nast, Thomas), an illustrator whose pen-and-ink cartoons blasted New York City's “Tweed ring,” a corrupt group of cronies associated with politician William Magear Tweed (Tweed, William Magear).

In the late 1920s Harper's began to emphasize public affairs; its contributors included figures such as the philosopher-historian Charles A. Beard (Beard, Charles A) and the philosopher-mathematician Bertrand Russell (Russell, Bertrand). The periodical balanced its primary concern for social and political issues with short stories by Aldous Huxley (Huxley, Aldous) and other contemporary writers. Increasing publication and postage expenses exceeded revenues in the late 1960s, causing Harper's financial problems to worsen enough that its parent company, the Minneapolis Star and Tribune Company, planned to close the magazine in 1980. At that point the John and Catherine MacArthur Foundation stepped in to establish the Harper's Magazine Foundation, an organization that continues to publish the magazine.

Under the editorship of Lewis Lapham, the magazine changed its format during the 1980s, adding a “Readings” section that featured an eclectic collection of reprints of interesting documents. It continued to publish original essays and fiction by prominent authors and maintained a generally liberal political philosophy. “Harper's Index,” a monthly feature, highlights statistics concerning political, social, science, and environmental issues. By the early 21st century, Harper's had a circulation of about 210,000.