Jean Guerrero is the author of the PEN-award-winning Crux: A Cross-Border Memoir , and an Emmy-winning investigative journalist at KPBS, the NPR and PBS affiliate in San Diego. The opinions expressed in this commentary are her own. View more opinion at CNN.

(CNN) President Donald Trump's prime-time address about the border wall Tuesday revealed his ongoing fixation with specific images and symbols at the expense of complex facts and Latin Americans.

He conjured images of "a steel barrier," "ruthless gangs," and "weeping mothers." Left out was mention of the diverse personalities, the varied backgrounds -- the humanity -- of the thousands of Central Americans who dream and plan and agonize about entering the US in quest of an image of their own: the American dream, el sueño americano.

Trump again stated that a wall is "absolutely critical" for border security. As a reporter covering the border since 2015 for KPBS and our public media partners, I've been investigating the effect of physical border barriers on flows of illegal immigration and drugs.

There is little evidence that existing barriers, construction of which took off in the 1990s under President Bill Clinton, have played a significant role in decreasing either of those things. But there is abundant evidence that they have rerouted those flows into other areas: into the desert, the ocean, the sky and underground.

Most of the activity that enriches transnational criminal organizations -- the smuggling of cocaine and other drugs -- occurs through legal ports of entry in cars . It's worth noting that a wall won't stop the southbound flow of the US guns those criminals use to protect their contraband -- the US guns that send Central American families north as they flee violence.

What the wall does do, and has been doing, is push illegal immigration into increasingly dangerous areas.

When Trump highlights American lives lost to people who entered the US illegally on prime-time television, he obfuscates other lives and other faces.

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Just last month, the body of a drowned Mexican man who tried to swim across the border washed ashore in south San Diego County. Every year since border barriers began to be erected, hundreds of people have died of dehydration or heat exhaustion trying to enter the US through the desert . I've seen the skeletons myself.

On three separate occasions, I've walked with Aguilas del Desierto, a group of farmworkers, plumbers and construction workers who spend their weekends finding the remains of lost migrants to give closure to the families of the lost. They follow vultures and the smell of baking flesh, or get rough directions from the coyotes who abandoned tired people.

Each time, we came across human remains, as well as countless abandoned items along the route: bibles being devoured by insects, crusty backpacks, empty gallon jugs.

In high school, I read a book called "The Devil's Highway" by Luis Alberto Urrea. It brought to vivid life a large group of migrants who tragically died entering the US through the desert in 2001. The book made me realize journalism could give voice to those without a voice, even the dead. The prospect of that power inspired me to pursue a career as a journalist.

Now, nearly 15 years later, the reality at the border remains largely the same as the one Urrea wrote about. The voices of the historically voiceless remain unintelligible, even as every major news organization sends journalists and photographers to the border.

Central Americans, and even Mexicans, aren't as relatable to a majority of US citizens as "the American blood" cited by President Trump in his address Tuesday night. Our literature, film and entertainment is still dominated by white male protagonists . Our empathy is shaped by the stories we hear and read as we grow up: Hemingway, Steinbeck, Melville.

When images of immigrants are used by the Trump administration, they are often used to stoke fear and resentment about "criminals" and "invaders" coming across the border. He mentions the women who are victimized -- sexually assaulted en route by those same criminals. President Trump has repeatedly used videos of the latest migrant caravan to dehumanize the group and to paint it as homogenous.

Meanwhile, his opponents have used images of mothers running from tear gas to stoke anger at Trump and sympathy for the migrants. What's lost in this tug-of-war over the meaning of photos and videos of real people is the complexity of their reality on the ground.

The caravan is not a homogenous group of people. Some plan to cross the border illegally -- and I've seen them jump the fence. Dozens have stormed the border, following the instructions of US-based left-wing groups, like BAMN , By Any Means Necessary, which distributes flyers at the camps. Others are willing to wait as long as it takes to ask for asylum in the US.

In Tijuana, at an impromptu Catholic mass in the street, I spoke to one desperate mother who fled Honduras with her 3-year-old son. Maria Edwina Perez told me she feared that a minority of unruly men in the caravan would ruin everyone's chances of entering the US by giving everyone a bad reputation. She faces weeks of waiting for a chance to speak to US immigration authorities because of backlogs at the ports of entry.

"If (Trump) doesn't want the men to enter, he should let the women enter. We come to work, not to create disorder. I am a daughter of God," she told me in a story for KPBS. "I am a peaceful woman with patience."

She recounted a dream in which President Trump let all of the children of the caravan flood into the US.