(CNN)While President Donald Trump is pushing forward with plans to build a wall between the United States and Mexico, tens of thousands of people are legally crossing the border between the two countries each day on foot.
While the proposed wall is intended to prevent people from crossing illegally, it's also a powerful symbol of separation between the United States and Mexico. But for the roughly 11.8 million people who live along the border, life on both sides is closely intertwined.
In 2016, 42 million people crossed into the United States using 16 pedestrian bridges -- and, with estimates from the Migration Policy Institute indicating that the population of the border cities will double in the next 30 years, the number of legal crossings should rise.
Many of them are Mexican citizens crossing into the United States to attend school, shop, and visit family. Some are US citizens who live in Mexico and work stateside.
Photos: Views from the border
The US-Mexico border spans 1,933 miles. It runs from the Pacific Ocean to the Gulf of Mexico, across California, Arizona, New Mexico and Texas. President Trump's pledge to build a wall along the border was a key part of his campaign. He said this month that early construction of the wall would be funded with US tax dollars in order to get started quickly, and promised that Mexico "will reimburse us." Click through this gallery to see scenes from the border and perspectives from those who live and work near it.
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Photos: Views from the border
Pamela Taylor, 88, has lived in Brownsville, Texas, since 1947. Taylor says she has had people from "all over the world" arrive on her property, and she says she has even found them in her living room. Every night, she fills a cooler in front of her house with bottles of water for migrants who made the journey, Border Patrol officers, or anybody else who finds themselves near the front steps of her house.
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Photos: Views from the border
Taylor put this sign up down the road from her house during the 2016 presidential election. She says that the fence the US government put up near her property in 2007 doesn't work. "I would like for Mr. Trump, I would even feed him, if he will come down here and talk to the people," Taylor told CNN. "He is doing exactly what the government did to us in the beginning. He's not asking how it's going to affect the people that live here."
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Photos: Views from the border
The Rio Grande forms a border between Texas and Mexico. Much of the river straddles remote desert and farmland, such as this stretch in Progreso Lakes, Texas.
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Photos: Views from the border
On October, 26, 2006, President George W. Bush signed the Secure Fence Act, and said, "This bill I'm about to sign is an important step in our nation's efforts to secure our border and reform our immigration system." More than 1,250 miles of the border are in Texas, but the state only has about 100 miles of man-made borders. This fence line in Progreso Lakes, Texas, comes to an end, and leaves miles of border land open.
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Photos: Views from the border
Greg Henington, owner of Far Flung Outdoor Center in Terlingua, Texas, says he doesn't believe a wall is necessary. "The wall is not going to make a difference one way or another. It's just going to cost a ton of money and look dumb."
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Photos: Views from the border
In 1935, the federal government passed legislation that would enable the state of Texas to acquire the land that would become Big Bend National Park. The park, known for its remote beauty, shares the border with Mexico for 118 miles and is separated by the Rio Grande.
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Photos: Views from the border
Lilia Falcon owns Jose Falcon's restaurant in Boquillas del Carmen, Mexico, across the Rio Grande from Big Bend National Park in Texas. The border crossing closed after September 11, 2001, and reopened in April 2013. "This town just went dead," Falcon told CNN. "We are very happy that the border is reopened again. We feel very safe here, even tourists that come over here, the word is spreading out more that its very safe to come here."
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Photos: Views from the border
Many Texas residents in the Big Bend National Park region believe that the various miles of remote canyons and rivers already act as an "effective barrier" with Mexico.
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Photos: Views from the border
Robert Cameron, owner of Texas Border Tours in Progreso Lakes, Texas, is in favor of President Trump's proposed wall, but he knows it will be complicated to build through parts with rough terrain. "I want to see a wall," Cameron told CNN. "Not a fence. I want to see a wall. I want to see something that you can't see through, that you can't climb through."
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Photos: Views from the border
The scenic mountains, canyons and desert that make up the Big Bend region on the west Texas-Mexico border span an elevation of less than 1,800 feet near the Rio Grande to almost 8,000 feet in the Chisos Mountains.
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Photos: Views from the border
Michael Ryan has worked as a ranger at Big Bend National Park since 1999, and 10 years as a river guide in the region previously. "It's not just one border, it changes depending on where you are," he told CNN.
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Photos: Views from the border
The Boquillas Crossing, a one-of-a kind port of entry where you can take a small ferry boat across the Rio Grande and into the tiny Mexican village, reopened on April 10, 2013, following federal closure for more than a decade after the September 11, 2001, attacks.
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Photos: Views from the border
Marcos Paredes has lived near Terlingua, Texas -- a former "ghost town" -- for much of his life. He spent years as a law enforcement officer responsible for patrolling the Rio Grande. "To come up with a one-sized fits all solution for illegal immigration is crazy," Paredes told CNN. "Because the border is so different along its entire links."
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Photos: Views from the border
Alicia Bon Martin, born in Nogales, Mexico, and her husband, Chris Martin, work and live on both sides of the Arizona-Mexico border. They own organic farms in Mexico, a produce distributorship, and the restaurant La Roca, a Nogales, Sonora, institution started by Alicia's uncle and celebrating its 45th year anniversary this year. "We are lucky because we have the good things of both sides," Alicia told CNN. "I see this border as a much calmer than anybody portrays it to be."
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Photos: Views from the border
Tim Foley founded The Arizona Border Recon in 2011, a nongovernment organization which provides intelligence to the US Customs and Border Protection. Foley has set up about a dozen cameras in the Sasabe, Arizona, desert and shares a database of smuggling activity that he says he captures with the Border Patrol. "It's a huge game of hide and seek," Foley told CNN. "A wall might help a little bit. But we have a wall here, or a fence, or whatever you want to call it. And it's not a deterrent -- it just slows them down for 10 seconds. So unless you have people watching the wall, it's not going to do anything. You need boots on the ground."
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Photos: Views from the border
There are about 700 miles of fence along the 1,933-mile international US-Mexico boundary. This stretch in Sasabe, Arizona, has a fence that was built in 2007. "I think a barrier, a physical barrier, is definitely necessary," Shawn Moran, vice president of The National Border Patrol Council, told CNN. "Putting up a fence, putting up a wall, has stopped the vehicle loads from coming across the border. It has been almost 100% effective in doing that."
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Photos: Views from the border
The westernmost part of the U.S.-Mexico border overlooks the Pacific Ocean, inside California's Border Field State Park outside San Diego, and adjacent to a public beach in Tijuana, Mexico. This area is known as Friendship Park/El Parque de la Amistad, a historic meeting place where generations from both nations have gathered to visit with family and friends "across the line."
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Photos: Views from the border
The Galvez tunnel was discovered by US authorities in 2009, approximately 20 yards north of the national boundary in Otay Mesa, California. The tunnel is about 6 feet high, 4 feet wide, and goes about 70 feet below Earth's surface. According to Homeland Security Investigations special agent Juan Munoz, their San Diego-based task force has discovered more than 29 of these sophisticated tunnels in the past decade.
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Photos: Views from the border
A US Customs and Border Protection officer patrols the fence in Otay Mesa, California. Patched holes in the fence are a common sight along this section of the border next to Tijuana, Mexico.
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Mexican citizens living in Mexico who have a valid passport can apply for a Border Crossing Card -- also classified as a B1/B2 visitor's visa -- that allows them to temporarily enter the United States. The simple act of applying does not guarantee them a crossing card. Cards are valid for 10 years, with some exceptions for cards issued for children.
California, Arizona and Texas allow US citizen children living in Mexico to attend public schools, though they must pay tuition. In New Mexico, public schools are open to all children of school age, regardless of residence.
The United States issued 1.1 million nonimmigrant visas to Mexicans citizens in 2016. 343,000 of those visas were issued at US consulates located along the border -- Ciudad Juarez, Nogales, Nuevo Laredo and Tijuana.
Here's a brief look at the busiest foot bridges connecting the United States and Mexico, and the border communities they've shaped.
San Ysidro Port of Entry
Number of people who legally crossed the bridge in 2016: 7.4 million
Number who cross each day: 25,000 people on average
What cities it connects: San Diego, California, and Tijuana, Mexico
When it was built: In the 1970s
The San Ysidro Port of Entry is one of the busiest crossings on the US-Mexico border, and one of three ports of entry in the San Diego-Tijuana region.
About a year ago, the world's first binational airport terminal opened in San Diego as an extension of the Tijuana Airport. A privately-funded skywalk bridge leads people from the city of San Diego directly into the Mexican airport, alleviating the wait times at the San Ysidro Bridge. Since its December 2015 opening, the bridge has welcomed 1.3 million travelers.
Tourism plays a big role in the volume of crossings at San Ysidro. American tourists have long been known to flood the streets of downtown Tijuana during spring and summer.
But among the bustling clubs and zebra-painted donkeys, there are also thousands of deportees in the city who find their lives in limbo. About 200 deportees arrive in Tijuana each day, according to Mexico's Migration Institute -- so many that the city has been nicknamed the deportee capital of Mexico.
The Migration Institute estimates that 70% of those deported to Tijuana speak English; many of them have no connection to Mexico, having left the country as young children. Situated just a few yards from the United States, immigrants deported to Mexican border cities like Tijuana often decide to stay there to remain close to the place they think of as home.
El Paso Port of Entry
Number of people who legally crossed the bridge in 2016: 7 million
Number who cross each day: 22,000 on average
What cities it connects: El Paso, Texas, and Juarez, Mexico
When it was built: The Paso del Norte bridge was originally built in the 1800s, though it has been rebuilt since then.
Some 600 to 1,000 children legally cross the Paso del Norte bridge to go to school every day, according to Customs and Border Protection.
Though the crossing between El Paso and Juarez is the second-busiest along the border, the region has not seen high levels of cross-border tourism over the years. After the terror attacks on September 11, 2001, border crossings were more strictly regulated, and it became harder for Mexicans to legally cross into the United States.
People had to wait in line longer, as many were searched and questioned about their whereabouts and intentions for crossing the border. Documents like state ID were no longer acceptable as proof of US residency or citizenship. More fencing went up along the border, and patrols increased.
In 2008, a wave of drug-related violence hit Cuidad Juarez and many Americans were discouraged from crossing into Mexico. Thousands of Mexican soldiers were sent to Juarez to fight the cartels who were held responsible for bloodshed. Juarez was dubbed the "world's most dangerous city," and it maintained that reputation until a couple of years ago. In 2010, Mexican officials counted 3,100 murders in Ciudad Juarez, an average of 8.5 killings per day.
Still, cross-border commuters continued crossing over for work and school.
The city began to see the number of homicides and crimes decrease around 2012. Today, it is no longer considered one of the world's deadliest cities and US economic investments have helped boost Juarez's economy. Several tourism campaigns targeting Americans seemed to have helped improve the city's image as the number of people who cross back and forth in El Paso-Cuidad Juarez has increased over the years.
Calexico Port of Entry
A plaque showing the boundary between the United States and Mexico at the Calexico Port of Entry.
Number of people who legally crossed the bridge in 2016: Approximately 4.3 million
Number who cross each day: 12,000 on average
What cities it connects: Calexico, California, and Mexicali, Mexico
When it was built: 1974
A pedestrian bridge connects the US city of Calexico -- a combination of the words California and Mexico -- with the Mexican city of Mexicali -- also a combination of the words Mexico and California.
Calexico recently became the scene of what's believed to be the first deportation of an active DACA recipient under the Trump administration.
In February, a 23-year-old Calexico resident, Juan Manuel Montes Bojorquez, alleged that he was apprehended and deported by US Border Patrol even though he had protected status under the Deferred Action for Childhood Arrivals program, which permitted him to work and go to school in the United States. Montes had been working as a farm laborer in Calexico and was expected to attend community college.
While DHS initially said that Montes' DACA status expired in 2015, they later said he did, in fact, have DACA status until 2018.
Montes says he tried to sneak back into the United States on February 19 and was caught by Border Patrol. Because DACA requires individuals to get preclearance to leave the country, Montes' reentry showed he had left without authorization and voided his status, DHS said.
Montes remains in Mexico and has filed a federal lawsuit asking that records be released for inspection as he disputes Homeland Security's claims.
