Ulloa Expedition Proves Baja is a Peninsula

In July 1539, Francisco de Ulloa sailed the Gulf of California to the mouth of the Colorado River and around the peninsula to Cedros Island, proving that Baja California is a peninsula.

People involved

• Francisco de Ulloa
• Hernán Cortés

When this happened

Ulloa Expedition Proves Baja is a Peninsula occurred in July 1539, during the colonial period period of American history.

Where this happened

Ulloa Expedition Proves Baja is a Peninsula took place in California. Explore the full history of California and primary source records from this era.

European colonization of North America accelerated after 1600, with England, France, Spain, and the Netherlands establishing competing settlements along the Atlantic coast, the St. Lawrence River, the Gulf of Mexico, and the Mississippi Valley. The first permanent English settlement at Jamestown, Virginia (1607) struggled with starvation and conflict; the Plymouth colony (1620) and the Massachusetts Bay Colony (1630) followed. By the mid-1700s, thirteen English colonies stretched along the Atlantic seaboard, governed through a mix of royal charters, proprietary grants, and elected assemblies. The colonial economy depended on tobacco in Virginia and Maryland, rice and indigo in the Carolinas, and maritime trade in New England — all increasingly reliant on enslaved African labor after 1619. Conflict with Indigenous peoples over land was continuous, punctuated by major wars including King Philip's War (1675–1676) in New England and the Yamasee War (1715–1717) in the South. The French and Indian War (1754–1763), part of the global Seven Years' War, ended French power in North America and left Britain deeply in debt — triggering the taxation disputes that would lead to revolution.

Content adapted from Wikipedia under the Creative Commons Attribution-ShareAlike 4.0 International License. Source: Wikipedia: Francisco de Ulloa.