<P> Before ratifying the treaty the U.S. Senate made two modifications: changing the wording of Article IX (which guaranteed Mexicans living in the purchased territories the right to become U.S. citizens) and striking out Article X (which conceded the legitimacy of land grants made by the Mexican government). On May 26, 1848, when the two countries exchanged ratifications of the treaty of Guadalupe Hidalgo, they further agreed to a three - article protocol (known as the Protocol of Querétaro) to explain the amendments . The first article claimed that the original Article IX of the treaty, although replaced by Article III of the Treaty of Louisiana, would still confer the rights delineated in Article IX . The second article confirmed the legitimacy of land grants under Mexican law . The protocol was signed in the city of Querétaro by A.H. Sevier, Nathan Clifford, and Luis de la Rosa . </P> <P> Article XI offered a potential benefit to Mexico, in that the US pledged to suppress the Comanche and Apache raids that had ravaged northern Mexico and pay restitutions to the victims of raids it could not prevent . However, the Indian raids did not cease for several decades after the treaty, although a cholera epidemic reduced the numbers of the Comanche in 1849 . Robert Letcher, U.S. Minister to Mexico in 1850, was certain "that miserable 11th article" would lead to the financial ruin of the US if it could not be released from its obligations . The US was released from all obligations of Article XI five years later by Article II of the Gadsden Purchase of 1853 . </P> <P> Before the secession of Texas, Mexico comprised almost 1,700,000 sq mi (4,400,000 km), but by 1849 it was just under 800,000 square miles (2,100,000 km). Another 30,000 square miles (78,000 km) were sold to the U.S. in the Gadsden Purchase of 1853, so the total reduction of Mexican territory was more than 55%, or 900,000 square miles (2,300,000 km). </P> <P> Though the annexed territory was about the size of Western Europe, it was sparsely populated . The land contained about 14,000 non-indigenous people in Alta California and about 60,000 in Nuevo México, as well as large Indian nations, such as the Papago, Pima, Puebloan, Navajo, Apache and many others . Although some native people relocated farther south in Mexico, the great majority remained in the U.S. territory . </P>

About how much of its property did mexico lose during the mexican-american war