For a long time, starting in the 1500s, Europeans held the belief that California was an island. This idea continued well into the 17th and 18th centuries, with maps of the region showing California separated from the mainland by a strait. Francisco de Ulloa, a Spanish explorer, reporting on his expeditions along the Baja California peninsula in 1539 was first responsible for propagating this myth. Father Antonio de la Ascension, the chaplain of the Sebastian Vizcaino expedition of 1602 who reported that California was separated from the rest of North America. Even after Father Eusebio Kino depicted a peninsular map of California in 1705, mapmakers continued the myth of California as an island. In 1771, English cartographer Herman Moll stated, ”California is undoubtedly an island. Why, I have had in my office mariners who have sailed round it.” Even with Spain’s King Ferdinand VII 1747 edict declaring that California is not an island, some cartographers continued to depict California as an island as late as the 1770s with cartographer DeVaugandy’s map.
Standford University has now made available online Glen McLaughlin’s “The Mapping of California as an Island: An Illustrated Checklist“. The book, published in 1995 by the California Map Society, lists 249 map entries focused on the depiction of California as an island. The cartobibliography starts with Dutch cartographer Abraham Goos’ 1624 map and lists entries chronologically up to Japan’s Shuzo Sato’s 1865 map.