One of the most famous misconceptions in cartographic history is of California as an island. The origin of this error is Las Sergas de Esplandian, a romantic novel written in 1510 by Garci Rodriguez de Montalvo, stating
“that on the right hand of the Indies there is an island called California very close to the side of the Terrestrial Paradise; and it is peopled by black women, without any man among them, for they live in the manner of the Amazons.”
This idealised view of California as a kind of Garden of Eden at the edge of the known world was negated by Father Eusebio Kino’s expedition from 1698 to 1701. Kino proved that Baja California, the (currently Mexican) peninsula which runs parallel to the mainland for hundreds of miles, is connected to it in the north.
Doubts remained, however, and the issue was finally laid to rest only with the expeditions of Juan Bautista de Anza (1774-1776).
It is somehow fitting that California, now home to the entertainment industry in general and Hollywood in particular, itself should be named after a fictional place first mentioned in a novel. Baja California was discovered in 1533 by a mutineer from Hernan Cortes‘ expedition into Mexico, followed by a trip by Cortes himself to that area (near present-day La Paz, on the southern tip of the peninsula). The lay of the land led him to believe this to be the island of ‘California’ from Montalvo’s novel.
Expeditions in 1539 and later seemed to indicate California was a peninsula, and at first it was thus shown on maps, including some by Mercator and Ortelius. Nevertheless, the idea of an insular California was revived, probably in part by the fictional accounts of Juan de Fuca. He claimed to have found a large opening in the western coast of North America, possibly the legendary Northwest Passage.
Further inspiration was the overland expedition by Juan de Oñate who descended the Colorado River (1604-1605) and believed he saw the Gulf of California continuing off to the northwest. California reappeared on the map as an island for the first time in 1622 in a map by Michiel Colijn of Amsterdam and this image would endure far into the 18th Century.
This map by Johannes Vingboons (1639) taken from the Library of Congress at this page.