Throughline (NPR): "Why the Wall Was Built"
Date: April 21, 2026
Hosts: Rund Abdelfatah & Ramtin Arablouei
Featured Guests: Anya Steinberg, Christina Kim (Producers); Rachel St. John (UC Davis historian)
Episode Overview
This episode—part of the limited-run "America in Pursuit" series—explores the little-known history behind one of the first barriers on the US-Mexico border. The story centers on Ambos Nogales, a city literally split by the border, and unpacks how a string of historical turning points transformed a "porous, ambiguous boundary" into a highly surveilled and policed frontier. The episode reveals that walls and fences weren’t first built primarily to prevent immigration as understood today, but to address customs, sovereignty, and incidents of cross-border violence.
Key Discussion Points & Insights
The Ambiguity of the Early Border
- Ambos Nogales—meaning "both Nogales"—existed as two towns, one in Arizona, one in Sonora, where people, goods, and services flowed freely. The border was poorly marked and more of a concept than a physical divide ([03:09]).
- Local entrepreneurs, like saloon owner John Brickwood, exploited this ambiguity—his establishment sat on the border, allowing tax-free sales of both American liquor and Mexican cigars ([03:23], [03:41]).
Notable Quote
"We speak of the two towns as one, for they are really such being divided by imaginary line only."
—Nogales, Arizona newspaper ([04:24])
Increasing Tensions & Need for Demarcation
- As the town expanded and border towns "got more heavily developed," government agents from both countries found it increasingly hard to know which country they were in ([04:43]).
- A boundary marker—a giant obelisk—was erected on Brickwood's saloon porch in the 1890s, signaling growing interest in clearly delineating the border ([05:12], [05:16]).
Notable Quote
“Customs officers start saying, you know, this is, it's impossible for us to police this space if people can just walk through John Brickwood's saloon."
—Christina Kim ([04:43])
Mexican Revolution & Rising Violence
- The Mexican Revolution (starting 1910) made border towns strategic for both revenue collection and power, inviting raids and increasing instability ([05:58]).
- The instability, paired with World War I fears of German spies, escalated cross-border suspicion, militarization, intelligence gathering, and the first real moves toward physical control ([06:33]).
The Spark: The Battle of Ambos Nogales (1918)
- On August 27, 1918, a deadly misunderstanding involving a Mexican carpenter sparked a gunfight. Customs officials on both sides shouted conflicting orders; a shot was fired (by whom is disputed), leading to over two hours of chaos and violence ([07:39]-[10:18]).
- The conflict was so significant it was immortalized in a Mexican "corrido", a ballad recounting local heroics ([08:43]-[09:52]).
Notable Quote
"There were 1500 gringos, all were federal troops, and the people of Nogales did not let them advance."
—Rachel St. John, translating the corrido ([09:04])
Memorable Exchange
Mexican consul tries to negotiate with an American soldier:
"If they both raised a white flag, it could all be over."
American soldier responds: "Go to hell. American troops don't carry white flags and don't use them."
([10:05])
- The outcome: Four Americans and 129 Mexicans dead, including the mayor of Nogales, Sonora, with hundreds wounded ([10:18]).
Aftermath: The First US–Mexico Border Fence
- Officials on both sides agreed on the necessity: "We need a fence. We need to be really clear about marking this space."
—Christina Kim ([11:04])
- The initial fence was constructed not as a migratory barrier, but to clearly demarcate territory and reduce tensions ([11:11]).
Notable Reflection
"Whenever I think about this, I think of the Robert Frost poem where he talks about how 'good fences make good neighbors,' right? ... This is not seen as an imposition ... but rather a joint effort to better demarcate where Mexican and American space end."
—Christina Kim ([11:19])
The Shift: From Customs to Immigration Enforcement
- Early fences weren't built to block Mexican migration; in the late 19th century, most U.S. concerns about southern border crossings were directed at Chinese immigrants ([11:53]).
- In 1924, the U.S. Congress significantly restricted immigration, established quotas, and created the Border Patrol—the infrastructures underlying today's border regime ([12:16]).
Notable Quote
"By the mid-1920s, the infrastructure of the border, the fences, the manpower and law enforcement ... the tools that we use today, were all in place."
—Rachel St. John ([12:32])
Modern Echoes
- Today, over 700 miles of border wall exist. The 2025 "One Big Beautiful Bill" under President Trump allocated over $170 billion, aiming to complete the wall by the end of his second term ([12:46]).
Timestamps & Segment Highlights
- [03:09] - [04:24]: Ambos Nogales’ merged social and economic life; “imaginary line” era.
- [05:12] - [05:16]: Erection of the boundary marker/obelisk on John Brickwood's saloon porch.
- [05:58] - [06:33]: Mexican Revolution; rise in violence, immigration, and smuggling.
- [07:39] - [10:18]: 1918 gunfight; the Battle of Ambos Nogales and its aftermath; the birth of the border fence idea.
- [11:11] - [12:16]: Construction of the first U.S.–Mexico border fence and shift toward immigration enforcement.
- [12:46]: Modern policies and the continuation of border wall expansion.
Memorable Quotes & Context
-
"We speak of the two towns as one, for they are really such being divided by imaginary line only."
—Nogales, Arizona newspaper ([04:24])
-
"So the US sent a survey team to mark the border more clearly. They put a new boundary monument and built it on the porch... A giant white obelisk."
—Rachel St. John ([05:07]-[05:16])
-
"Whenever I think about this, I think of the Robert Frost poem where he talks about how 'good fences make good neighbors,' right?"
—Christina Kim ([11:19])
-
"The fence wasn't about keeping Mexican people out of the U.S.—no one cared about immigration at all on the U.S.–Mexico border until very late part of the 19th century."
—Rachel St. John & Christina Kim ([11:53]-[11:58])
Conclusion
This Throughline episode reveals that the wall on the US–Mexico border wasn’t originally about immigration, but about customs control, local tensions, and responding to violence and wartime paranoia. Physical barriers—originally joint, ambiguous undertakings—morphed over decades into rigid symbols and tools of national sovereignty and exclusion. The episode invites listeners to reconsider common assumptions about the southern border by tracing the “wall’s” little-known, multifaceted origins.
