In this country, car pooling is generally seen as a way to help the environment and reduce greenhouse gas emissions.
But a lot of people don't have to do it, if they don't want to.
In Mexico, it's a different story. For many workers, car pooling isn't just a socially conscious thing to do. It's the only way to get to work.
These photos were taken by Alejandro Cartagena. They're part of a project he was doing for a research institute, on how people use the streets in Monterrey.
As you can see, the trucks are pretty crowded at times - out of necessity. As Cartagena told Slate...
"Construction workers were buying houses an hour or more away from where they worked and there is no public transportation for them, so I started documenting how people used their cars," he said.
"How they drive to work or drive home, how they personalize their cars based on the neighborhoods in which they lived, and I started looking down from buildings and bridges to see how cars looked. It's not uncommon to see the carpoolers, but I had never seen them from that perspective."
Cartagena spent a day or two a week taking the shots - some days, he'd only get one; other days he'd get five.
"Typically Thursday and Friday were the best because it's payday so you get a lot of people going to work," he said.
As for the impact of the photos, Cartagena said "There is a bit of humour to a social issue, a lightness where you can also wonder what is really happening. It's also an intimate space."
"They're reading papers, sleeping, chatting with friends. It's kind of a living room on the back of a truck - things are happening in a living room, but it's also in a public space."
His work was recognized at the Sony World Photography Awards in 2012.
And this week, they'll be on display in an exhibit called 'Car Poolers', at the Kopeikin Gallery in Los Angeles from Feb. 23 to April 6.
"I guess people responded favorably because there are so many things represented in the pictures," he told Slate. "People think the men are crossing the border illegally or there are dead bodies in the trucks."
"I think there are so many interpretations because the images are so simple."
You can see more of Cartagena's photos on Slate's website here.