Why Did the USA Not Take Baja California?

The United States ultimately did not acquire Baja California following the Mexican-American War primarily because of its close geographical relationship to the Mexican state of Sonora, located just across the narrow Sea of Cortés.

Historical Context: The Mexican-American War and Treaty of Guadalupe Hidalgo

The Mexican-American War, fought between 1846 and 1848, significantly altered the territorial landscape of North America. Following the U.S. victory, negotiations commenced for a peace treaty that would define the new border between the two nations. This monumental agreement, known as the Treaty of Guadalupe Hidalgo, was signed on February 2, 1848.

The treaty resulted in Mexico ceding vast territories to the United States, including present-day California, Nevada, Utah, Arizona, New Mexico, and parts of Colorado, Wyoming, Kansas, and Oklahoma, in exchange for $15 million and the assumption of Mexican debts to U.S. citizens. However, despite its strategic location and potential, Baja California was notably excluded from this massive land transfer.

The Negotiation Process: From Inclusion to Omission

During the initial phases of the treaty negotiations, the acquisition of Baja California was indeed on the table. The original draft of the Treaty of Guadalupe Hidalgo actually included the peninsula as part of the territories to be sold to the United States. This suggests an initial American interest in controlling the entire Pacific coast, including this long, arid peninsula.

The Decisive Factor: Proximity to Sonora

Despite its initial inclusion, the United States eventually agreed to omit Baja California from the final sale. The critical reason for this decision was its proximity to the state of Sonora, which lies directly across the narrow Sea of Cortés (also known as the Gulf of California). This geographical closeness posed a specific consideration for negotiators. While the exact strategic implications were not fully documented in the public record, it's understood that this tight geographical bond between Baja California and Sonora influenced the decision to keep the peninsula as part of Mexico.

The table below summarizes the key aspects of Baja California's fate during the treaty negotiations:

This omission ensured that the Mexican mainland, particularly the state of Sonora, maintained direct contiguity with its peninsula across the gulf, avoiding a complex geopolitical arrangement where U.S. territory would closely flank a vital Mexican state across a narrow body of water.