This idea for this note came from a recent short documentary by Frontline World.
Queues can sometimes have interesting implications. In the graduate classes that I took, we learned something fundamental: if demand exceeds supply, queues will explode. And since exploding queues bring daily affairs to a standstill, those who want to bring such queues under control have to give in to other things - like the US border patrol, which has to yield to persevering illegal immigrants.
The San Ysidro checkpoint near San Diego is the busiest border crossing in the world. On the Mexican side of the border is the city of Tijuana, famous as a hotbed of drug cartel activity, but also full of immigrants wanting to make it to the US. In fact, there is even a patron saint – Juan Soldado, a soldier who died in the 1930s – worshiped by those attempting to cross illegally.
More than 18 million people - legal and illegal - pass through San Ysidro every year. The queues are so long that the officers at the checkpoint can only selectively choose and check the cars; the line has to be kept moving. The officers have to rely on demeanor – if the driver is nervous, or something looks suspicious, the vehicle will be checked. And sometimes illegal immigrants will emerge from cleverly hidden compartments in dashboards.
But most vehicles go unchecked, so many immigrants are able to get through. Even if they get caught on the US side, the length of another type of queue, the queue of those waiting to be prosecuted, makes it impossible to detain them. Federal courts in the US just don’t have the capacity. So the illegal immigrants are simply sent back to Mexico. They smile and joke as they return. They know they can come back; there is no limit on how many tries you make. And that's because the human smuggling business has a remarkably customer friendly – or rather prospective illegal immigrant friendly – deal: you pay only after you are safely across.
Mathematically, it can be shown that virtually everyone attempting to cross – provided he or she can pay the required $2000 dollars upon crossing – will eventually make it through with enough tries. The pressure of queues in conjunction with a “money after service” deal creates an easy loophole immigrants can exploit.