At the stroke of a pen, the Treaty of Guadalupe Hidalgo converted 525,000 square miles of Mexican lands into U.S. territory, including what later became California.

The treaty marked the origin of the current border as well as a watershed moment in the westward expansion of the United States. USC’s acquisition is a windfall to faculty studying the history of the border and its impact on people living in both countries.

“The Treaty of Guadalupe Hidalgo is the most important document in United States history after the Constitution and the Declaration of Independence,” said Michael Dear, professor and chair of USC’s department of geography. Along with the USC Libraries’ collection of maps and photographs from border-drawing expeditions in the 1850s and 1890s, the treaty “tells our nation’s origin story,” Dear said.

The treaty arrived at USC as the result of a 20-year quest to bring this rare edition – one of only 17 in the United States – into the USC Libraries’ collections. “I’ve been trying to acquire the treaty since I came to USC in 1985,” said Barbara Robinson of the Boeckmann Center for Iberian and Latin American Studies.

Robinson met success when she found an original edition up for bid at Christie’s auction house and acquired it immediately. “It’s even more unusual to find one in such pristine condition,” Robinson said. USC’s copy joins only three others residing at Los Angeles-area libraries.

The treaty has caught the attention of scholars pursuing subjects across many disciplines. “It will be extremely valuable to students and faculty alike,” said Selma Holo, director of the USC College’s International Museum Institute and professor of art history.

Holo’s interests include the relationship between art, museums and national identity in Mexico. “Given the gratifying leap in our commitment to border research at USC, the acquisition of the Treaty of Guadalupe Hidalgo is yet another milestone that we can celebrate together.”

The rare original edition now held in Doheny Memorial Library tells aspects of the border’s story that aren’t widely known. For example, it shows the terms originally agreed upon by negotiation teams from Mexico and the United States. President Polk and Congress later made significant changes to the treaty that resulted in Mexican nationals losing millions of acres of privately owned land.

The USC Libraries’ copy also includes commentary by one of the Mexican negotiators revealing how he believed the treaty would influence future relations with the United States.

Such details are essential to understanding the complex political and cultural forces that shape the meaning and physical location of la linea, Dear said. “Reading the original text takes you back into the time period you’re studying, so that your work is contextualized and grounded in history. The border isn’t just a line; it’s everywhere. I’m interested in understanding its periodization and its regionalization – that is, exactly when and where it took shape.”

The Treaty of Guadalupe Hidalgo joins a wealth of related materials in the Boeckmann collection, including the 1836 treaty that granted Mexico’s independence from Spain and photographs of stone markers and monuments from the 19th-century border surveys.

As the collection grows, Dear and Robinson expect to see many research projects by students, faculty and scholars in Mexico and the United States seeking fresh insights into the border. Dear’s own research falls into that category.

“I’ve traveled the length of the border on both sides, and I’m struck by how it is becoming a harmonious, single community,” Dear said. “A third nation is being born between the two countries that has no time for borders or walls. It is just getting on with creating a new world of its own, separate from D.C. and Mexico City.”

Anticipating the digital future of border studies, Dear’s work has evolved into an “archaeology of the border,” encompassing everything from Aztec codices that depict the pre-Columbian cultural life of the region to satellite images that document the rapid growth of population centers along the border since the late 20th century.

To that end, Dear has secured pilot funding from National Geographic and already has consulted with USC Libraries technical experts to begin digitizing significant print holdings like the Treaty of Guadalupe Hidalgo. The collection will form what Dear calls the “archival base” of his digital border project.

“Creating a widely accessible digital tool is absolutely necessary to promoting border scholarship,” Dear said. “Our project will let researchers traverse a digital representation of the border in both time and space. It will draw on the library’s print, cartographic, art and photographic resources to enable new ways of looking at the border.”