How the war began

Be honest: What do you really know about the Treaty of Guadalupe Hidalgo?

The accord that formally ended the Mexican-American War (1846-48) radically altered the destinies of both countries. So crushing was the defeat of Mexico that the United States demanded and received Texas, California, Nevada and Utah as well as big slices of Arizona, Colorado, Wyoming and New Mexico.

Imagine the U.S. without all that territory. Imagine Mexico with it.

And yet how did the 1848 treaty come about? What does it actually say? And how did it affect those living on both sides of the new border, including Native Americans and African Americans, whose destinies were decided without their consent?

A new pop-up exhibit at the Bob Bullock Texas State History Museum in Austin helps clear the air.

“Legacies of the Treaty of Guadalupe Hidalgo” represents a relatively new type of show for the Bullock, which opened as the premier museum on the subject of Texas history in 2001. The pop-up exhibit, which lasts through Feb. 16, 2025, includes pages – originals and copies – of the treaty, on loan from the National Archives.

As the museum slowly updates and upgrades its permanent exhibit – the modernized rooms on the ground floor dedicated to early Texas were unveiled in 2018 – the more recent curatorial work upstairs has evolved one room at a time.

The treaty popup show, located on the museum’s second floor, offers senior curator Kathryn Siefker the opportunity to rethink what will permanently fill that gallery.

“We had been talking about the Treaty of Guadalupe Hidalgo for a long time,” Siefker says.

In a blue-tinted room under low general lighting, the sharply defined individual displays of “Legacies of the Treaty of Guadalupe Hidalgo” examine the times before, during and, especially, after the world-changing agreement.

They cover the basic contours of the Mexican-American War, which started in 1846 after 30 years of regional chaos. The U.S. insisted that Mexico’s border with the recently annexed Texas run along the Rio Grande, which the Republic of Texas had claimed, rather than the more northerly Nueces River, which Mexico recognized.

President James K. Polk dispatched Gen. Zachary Taylor to the Texas coast to secure the land between the rivers, known as the “Nueces Strip.” Supplies and troops were funneled through Lavaca and Corpus Christi. Old Bayview, a hilltop cemetery laid out in 1845 in the latter city, is the oldest federal military graveyard in the state.

To Mexico, the military move into the strip represented clear provocation.

An image on display at the Bob Bullock Texas State History Museum in Austin, Texas, shows one of the monuments planted on the U.S. border with Mexico after the Treaty of Guadalupe Hidalgo.

The Battle of Palo Alto, just north of the Rio Grande, previewed later clashes in Mexico’s interior. The U.S. Army generally dominated its opponents. Ulysses S. Grant, at the time a lieutenant, observed the stark brutality visited on Mexican civilians by the Texas Rangers, who joined the federal forces. Meanwhile, halfway across the continent, American explorer John Frémont was fomenting rebellion in California against Mexican rule.

After U.S. forces occupied Mexico City, the nation, already weakened by decades of infighting, was doomed. As peace negotiations began, many in Mexico resisted the loss of any of its sovereign territory. Yet the U.S. took half of it. The U.S. agreed to pay for Mexican damages in the war, among other concessions.

Pages of the treaty borrowed from the National Archives – including both early “dirty” and later “clean” copies, to demonstrate which articles were eventually left out – will be rotated during the run of the show. Currently on display is an excerpt stipulating that the U.S. end its blockade of Mexican ports and withdraw its troops from Mexico, especially from Mexico City.

PROVIDED BY THE NATIONAL ARCHIVES