Beyond Thirty is a short science fiction novel by Edgar Rice Burroughs. It was written in 1915 and first published in All Around Magazine in February 1916, but did not appear in book form in Burroughs' lifetime. The first book edition was issued by Lloyd Arthur Eshbach's Fantasy Press fanzine in 1955; it then appeared in the collection Beyond Thirty and The Man-Eater, published by Science-Fiction & Fantasy Publications in 1957. The work was retitled The Lost Continent for the first mass-market paperback edition, published by Ace Books in October 1963; all subsequent editions bore the new title until the Bison Books edition of March 2001, which restored the original title.
The story was heavily influenced by the events of World War I, and reflects U.S. sentiments at the time of writing. When the war broke out, Americans were predominantly isolationist and wary of being drawn into a European war. Burroughs imagines a future two centuries onward in which that view prevailed and the western hemisphere severed contact with the rest of the world. Consequently, the eastern hemisphere has exhausted itself in war and Europe has descended into barbarism while the Americas, sheltered from the destruction, have continued to advance and joined peacefully into the union of Pan-America. By the twenty-second century the entire world east of the 30th meridian west and west of the 175th meridian west has become terra incognita to Pan-America.