Borders are an important concept, both symbolically and literally, in The Devil's Highway, by Luis Alberto Urrea. The border is what needs to be crossed to transform lives, and this is most obvious in the economic ramifications for the border crossers who are led and those who "guide" them.
The motivation to cross the border for Mendez (Rooster), for example, is purely an economic one, a ruthless desire to make money. The opposite side of the economic picture is the moral picture. The morality of crossing the border is a non-issue when economic concerns such as job prospects, making a living, or running a business come into play—not just for Mendez, but for the impoverished men from Veracruz. Morality is pushed aside by the crossers but is arguably a central motivation of the Border Patrol is their quest to capture border crossers and keep the border safe.
Borders shape cultural identity and evolve as the cultural norms change: fifty or sixty years ago, Mexicans crossed a barely perceptible border on their way to work or live in San Diego or Los Angeles but today those crossing points are heavily guarded. The cultural norms of what makes a border changed in the 1980s, then transformed through NAFTA in the 1990s, and today cultural borders live on in policies that persecute people who have immigrated to the US from Mexico or Central America. The cultural borders are perhaps more important than any others, because of the unbending attitudes on both sides of the border due to cultural differences between Mexico and the US.
Political borders are largely geographic, those lines drawn through historical battles or local agreements that separate the US and Mexico. In some remote places, like the far southern reaches of Texas near the Rio Grande river, these borders don't matter matter culturally, barely matter economically, and make no difference morally—but politically they are fought over as if they are as important as the border between Tijuana and the US.
Our culture, whether American or Mexican, is shaped by economic borders because of opportunity, by moral borders because of the context of individual morality, culturally because we need our cultures to strengthen borders, and politically because we can become hostages to arbitrary political decisions on both sides of the border. In The Devil's Highway, the history of the area where these men crossed and died tells the story of a border that has shifted radically over a few hundred years.