What significant event defined the international boundary between Mexico and the United States in 1848?

The Treaty of Guadalupe Hidalgo is significant because it formally ended the Mexican-American War in 1848 and established the current international boundary between Mexico and the United States. Under the terms of this treaty, Mexico ceded a vast portion of its northern territories, including present-day California, Nevada, Utah, Arizona, and parts of Colorado, New Mexico, and Wyoming, to the United States. This territorial acquisition not only reshaped the map of North America but also had lasting effects on the cultural and political landscape of both nations.

The Treaty of Paris, while important in American history, was related to the conclusion of the Revolutionary War with Great Britain in 1783 and does not pertain to the boundary between Mexico and the United States. The Treaty of San Francisco does not exist in this context and is likely a confusion with another treaty relevant to Asia or other historical events. The Treaty of Tordesillas, signed in 1494, aimed to divide the newly discovered lands outside Europe between Spain and Portugal and has no relevance to the boundary shaping between Mexico and the United States.