Border closures like the one that happened late last month after an ill-fated march, are extremely rare – and businesses at the border hope it stays that way.
After a group of migrants ran around a Mexican Federal Police blockade and towards the border , the entire San Ysidro Port of Entry was shut down for roughly five hours.
Jason Wells, the executive director of the San Ysidro Chamber of Commerce, sent a letter  to U.S. Customs and Border Protection Tuesday expressing his concerns over the closures.
“The San Ysidro Chamber of Commerce understands these are extraordinary times for all with regards to the Central American Migrant Caravan’s (“caravan”) arrival to Baja California,” Wells wrote in the letter. “However, we still have lives to live, an economy to drive and livelihoods at stake. For these reasons, we must ask that closing our port of entry to subdue pedestrian chaos-seekers not be an option.”
Even before last Sunday’s events, Wells wrote, a week earlier the San Ysidro Port of Entry “was completely shut down due to a rumor that a pedestrian group might approach the border. We simply cannot live like this; and rhetoric from Washington, DC threatening spiteful and longer-term closures exacerbates the situation.”
Stopping traffic at the port of entry or significantly disrupting its flow has a huge financial and human cost, especially for communities along the border. Commercial exchange between San Diego and Tijuana is estimated at $2.1 million  a day. Last Sunday’s five-hour closure at the border cost businesses in San Ysidro, which depend on cross-border traffic for their yearly profits – particularly between Thanksgiving and Christmas – $5.3 million. The losses to Tijuana businesses were equivalent to roughly $6.5 million .
More common than outright shutdowns are closures of some crossing lanes – those have been reduced for years as the San Ysidro Port of Entry has been construction as part of an expansion.
The last time the San Ysidro Port of Entry was closed was in 2011 and was related to construction –scaffolding fell , injuring two dozen people. Vehicle lanes into the United States were closed immediately after the collapse, but partially re-opened later that day. During Sunday’s closure, lanes in both directions were closed and pedestrian traffic was stopped.
Before that, two major events impacted the border: the 9/11 terrorist attacks, and the kidnapping, torture and murder of DEA Agent Enrique “Kiki” Camarena in 1985.
After Camarena’s disappearance, several ports of entry were closed along the U.S.-Mexico border and the others faced ramped-up security and vehicle inspections to pressure Mexican authorities to help find Camarena.
In the aftermath of 9/11, the San Ysidro Port of Entry remained open, though border traffic slowed significantly due to new security protocols. The slowdown was so intense, the city of San Diego declared an “economic emergency,” according to a paper  by Brown University professor Peter Andreas.
Cross-border trade along the entire southwest border, which had been running at about $670 million, fell by an average of 15 percent in the weeks following the attacks, Andreas wrote. The most severely affected businesses were electronics, textiles, chemicals and Mexican factories supplying parts to U.S. auto companies.
“While a sustained enforcement crackdown at U.S. land ports of entry may help to reassure and calm a nervous public, in practice it may do more to inhibit legitimate travel and trade than terrorists,” Andreas said.
According to data  from the Crossborder Group, a border consulting firm, on Sept. 11, 2001, car crossings at the San Ysidro Port of Entry dropped by roughly 44 percent. On Sept. 12, 2001, they fell by 62.2 percent. That entire week, 48 percent fewer cars crossed than the week prior.
A phone survey done by the Crossborder Group after 9/11 found  that 74.5 percent of southern San Diego retailers reported a drop in sales after 9/11 – with an average drop of more than 25 percent.
There is no doubt that security scares at the border have ripple effects that far outlast the closures themselves. And as short 10-minute closures at various ports of entry throughout San Diego County continue for “readiness operations,” Wells worries that the federal government will close the border more frequently, instead of as a final option.
“Every time there is an issue now, it seems to be easier for them to pull the trigger,” Wells said. “At the end of the day, we want our borders to be secure. They have to be ready, I do understand that. But closures should be a last resort.”
Josiah Heyman, director of the Center for Interamerican and Border Studies at the University of Texas at El Paso, who has been writing about ports of entry for more than a decade, said even with last Sunday’s events, the Central American migrants in Tijuana should be at the bottom of the security risk continuum for the U.S. government.
“The most important thing is that the current U.S. policy at the border, both between ports of entry and at ports of entry is totally disconnected from security,” Heyman said. “Any sort of reasonable, rational account of security would be focused on screening for high-risk shipments and materials, like drugs like fentanyl crossing through ports of entry and screening for small numbers of dangerous of people.”
Some of the migrants might not meet the strict qualifications for asylum in the United States, but that does not make them security threats, Heyman said.
“Those are important legal and moral questions, but it’s not a matter of border security,” Heyman said. “This is a created crisis, the blockading people in Mexico, who are then freaked out and confused.”
Alan Bersin, former “border czar” under President Bill Clinton, who also served in several Department of Homeland Security posts during the Obama administration, including acting commissioner of Customs and Border Protection, said he views the border closure last Sunday as an adequate reaction to the events that transpired.
“The idea of closing the border is a radical move,” Bersin said. “When you see the kind of threat of illegal migration that was present last Sunday, any administration would be inclined to stop cross-border movement. It wasn’t security, it was reaction.”
In that sense, Bersin said, what happened last Sunday was similar to what happened following 9/11 and Camarena’s disappearance – it was a reaction to unforeseen events.
Wells said closures and the threat of them are changing his organization’s role as a Chamber of Commerce. Instead of just marketing and supporting his members, he now has to act as a constant source of information on planned closures as well as potential events in Tijuana that could lead to other disruptions.
In his letter, Wells asked the federal government that while it’s investing in security between the ports of entry, to invest in the ports of entry themselves. His suggestion was to invest the equivalent of the annual economic output of San Ysidro and the San Diego-Tijuana region, $678 million and $220 billion respectively.
“We must, to recuperate losses from the previous border closure, promote San Ysidro as ‘open for business.’” Wells wrote. “We must promote, during this high travel season, the binational tourism that keeps the San Diego region afloat. We must keep a way of life that employs thousands in the South Bay of San Diego. But we can do none of this without a commitment from you to keep our doors open.”