Final answer:
False. Mexico lost more than half of its territorial land mass as a result of the Treaty of Guadalupe Hidalgo.
Step-by-step explanation:
False. The Treaty of Guadalupe Hidalgo, signed in 1848, ended the Mexican-American War and resulted in Mexico ceding approximately half of its territory to the United States. This included the present-day states of California, Nevada, Utah, Arizona, New Mexico, and parts of Colorado, Wyoming, Kansas, and Oklahoma. So, Mexico lost more than half of its territorial land mass as a result of the treaty.