Oaxaca, Mexico - Parks in Latin America serve a number of purposes. They provide a green respite in an otherwise concrete jungle. They're a space where anyone from the wealthy to the homeless can rest their legs. And, for young couples, they're the most popular place to hook up.

In the park in southern Mexico where I'm writing this article, all four benches adjacent to me are currently occupied by young lovers, and another couple (whose bench I'm rudely occupying) is sprawled out in the grass. I was lucky to get a seat. I showed up early.

If public displays of affection make you uncomfortable, don't come to Latin America. Unlike the United States, there's no room for pearl clutching here. From Mexico City to Medellin and Buenos Aires to Belize, making out in public is a virtual rite of passage for high schoolers and young adults.

It's so widespread that when the city of Guanajuato passed an ordinance in 2009 banning certain forms of PDA, it was met with such furor that the law had to be suspended days later. Nobody has since dared to tell youngsters to "get a room."

What's behind this phenomenon?

Why is hooking up in public so ubiquitous in Latin America, yet so rare up north?

In Oaxaca, the capital city of the state of Oaxaca and my current home, I speak with a number of young Mexicans about why making out on park benches is so popular. I might as well ask them why they are wearing clothes. "Everyone does it. It's not a bad thing," one 14-year-old boy says, though he insists he doesn't participate. "Being seen in public isn't a concern."

Alexis Mendoza, 22, puts on a mischievous grin when I ask him about his experience with public fajar — a term commonly used in Mexico for making out, but is literally translated as "to swaddle." His explanation is one I hear over and over again: "There isn't any space in my house. There's much more room in the park."

Housing statistics back up Mendoza's point. According to national census data, there are two people for every one bedroom in an average Mexican household. It's even more cramped in the state of Oaxaca, where there are an average of 2.3 people for every bedroom. In other words, not much privacy. (Three-quarters of American homes, by contrast, have one person per bedroom or fewer.)

With little personal space for young lovers in a typical Mexican home, parks have become an escape from cramped and inhospitable living quarters.

I ask two sisters, Alma and Herminia Martinez, both in their mid-20s, if it would be acceptable for them to bring a boyfriend home. The horror that ripples through their faces suggests this is unquestionably prohibited.

"Why not?" I ask. Alma is blunt: "los papás." Dads. "They set the rules of the house, and they're old-fashioned, especially with daughters," she says. "No bringing boys home." It's still a machisimo society, after all. And even if an individual family might not object, the power of gossip when a neighbor sees a young man accompanying a young woman home is not to be underestimated.

Another factor interviewees point to is the simple fact that it doesn't cost anything to hook up in public. Going to the movies costs money. Cafés cost money. Dinner costs money. Very few young people have cars. A park bench, on the other hand, is free.