“You got to be able to laugh at the Gadsden Purchase. It’s what life is all about.” So said Mike DiCenzo, a longtime writer for Jimmy Fallon, who played an audience member in a delightful bit that aired in March 2009.

“Look at all the comedic possibilities,” DiCenzo added. “You’ve got [President] Franklin Pierce. Hello? And James Gadsden. Not to mention topographical issues regarding the construction of the transcontinental railroad.”

“I mean the jokes practically write themselves.”

The skit is very funny. But in many respects the largely ignored Gadsden Purchase is not a joke at all. Rather, it has a bizarre and illuminating history that involves leading pro-slavery politicians and the future of slavery, the often blurry line between business interests and public policy, and the still fraught relationship between the United States and Mexico.

Via the Purchase, the US, in 1854, acquired 29,670 square miles of land, most of it in what is now southern Arizona and some in southern New Mexico. The first draft of the treaty was signed on December 30, 1853, by James Gadsden, U.S. envoy to Mexico, and Antonio L—pez de Santa Anna, president of Mexico. The 100th anniversary of that event was commemorated in today’s #stampoftheday, a 3-cent stamp issued on December 30, 1953. (The final treaty went into effect in June 1854).

While almost 30,000 square miles is a lot of land, the purchase only looks like a sliver of land on a map of the US, particularly one that shows that ways that the country grew. In the Louisiana Purchase of 1803, for example, the US added 828,000 square miles of land in what became all or part of 15 states. And the 1848 treaty ending the Mexican-American War led to the addition of about 525,000 square miles of land in what became all or part of six states.

This helps explain why the Gadsden Purchase is often overlooked. But there’s more to the purchase than its relatively small size.

In addition to resolving some lingering issues from the treaty that ended Mexican-American War, the purchase’s main purpose was to give the US control of land needed for a proposed southern transcontinental railroad line that would avoid difficult mountainous crossings. The proposed route was strongly backed by several pro-slavery southerners, notably Gadsden, who in the 1840s had served as president of the South Carolina Rail Company (a predecessor of the Norfolk Southern Railway). Gadsden and other southern leaders – including Jefferson Davis, who later was the president of the Confederate States of America – believed that a transcontinental railroad on the southern route would strengthen the economy of slave states and perhaps pave the way for the admission of more slave states. They also feared that two proposed alternatives, a central and northern route, would fuel further economic growth in the northern, non-slave states.

Gadsden, moreover, was a strong proponent of slavery. In 1850, when California was admitted to the union as a free state, he called for South Carolina to secede from the Union. When that effort failed, he actively supported an effort to split California into a free state and a slave state where he wanted to establish a slaveholding colony based on rice, cotton, and sugar. In fact, in the spring of 1852, Gadsden and 1,200 potential settlers from South Carolina and Florida submitted a petition asking the California state legislature for permission to establish a rural district that would be farmed by “not less than Two Thousand of their African Domestics.” (Although it stimulated some debate, it died in committee.)

Franklin Pierce, a Democrat from New Hampshire who was elected president in 1852, was supportive of the southern rail route and other measures backed by southern Democrats. He appointed Davis as his secretary of war and Gadsden as his envoy to Mexico, with instructions to purchase land from Mexico needed to resolve the treaty issues and facilitate the railroad’s construction.

Gadsden met with Santa Anna, a former president who had been exiled, who had recently returned to power. Santa Anna was willing to deal with the United States because he needed money to rebuild the Mexican Army. Moreover, he feared that the US might well again go to war with Mexico and seize territory it wanted without any payment. Seeking to get as much money for as little territory as possible, he ultimately agreeing to sell the about 30,000 square miles of land for about $10 million (roughly $230 million in current dollars).

While Gadsden succeeded in getting the land needed for the southern rail route, because of growing disputes about slavery Congress was unable to agree on a route (or routes) for the proposed railroad. Finally, in 1862, more than a year after southern states had seceded from the union, it chose the central route. Two decades later, however, a second transcontinental railroad was built using some land acquired in the Gadsden Purchase.

In Mexico, displeasure with the sale (including assertions of corruption) led to Santa Anna being forced from office in 1855. Moreover, the bitter feelings about the sale continue to linger, according to Josefina Zoraida V‡zquez y Vera, professor emeritus in history at the Colegio de Mexico in Mexico City. “It was resolved by force the way the United States always resolves things,” she told the Arizona Star in 2004. “They claim it was a sale, but it wasn’t a sale. Mexico was not in the best of conditions and Santa Anna decided on the path of conciliation in order to avoid another war….It continues to affect our relationship, not as much as the war with the United States, but obviously, it is one of the major cases we make against American policy.”

So the joke isn’t, as DiCenzo suggested, that the treaty is obscure, The joke is that its connections to slavery and to troubled relations with Mexico haven’t gotten the attention they deserve.

Be well, stay safe, fight for justice, and work for peace.