A visitor looks at a photo of cell phones confiscated from migrants at the exhibition.

During a decade as a janitor at a US border station, Tom Kiefer gathered the trash left behind by thousands of undocumented immigrants, piecing together the histories of those who arrived seeking a better life.

Everyday objects from clothes, medicine and toys to handwritten letters were confiscated by officials as dangerous or "non-essential" items, leaving photography student Kiefer to sift through fragments of their owners' struggles.

"El Sueno Americano/The American Dream", at Los Angeles's Skirball Cultural Center through March, displays more than 100 photographs of these remnants, which the artist collected in secret at the Ajo, Arizona station between 2003 and 2014.

From a distance, many of the works look like abstract modern art, but peer more closely and the contents become clear: in one, dozens of syringes and cartons containing pills and ointments are carefully laid out across a bright yellow canvas.

Close by, around 50 toothbrushes -- some extremely worn-out and filthy -- are arranged on a blue background.

Another photograph captures cell phones of all shapes, sizes and technologies spanning the decade.

Dominga Rodriquez, 48, originally from Mexico, visits the exhibition.

For Dominga Rodriguez, a 48-year-old who crossed through the desert from Mexico's Oaxaca state almost 30 years ago, it is easy to picture the faces of these items' owners.

"It's emotional because I also came in the same way," she told AFP as she visited the exhibition, her voice cracking. "We left our clothes, combs, wallets, phone numbers, not knowing if we were coming back or not."

Every year, hundreds of thousands of undocumented immigrants are detained while crossing into the US from Mexico.

Curator Laura Mart stands beside a photo called "Trail Markers" showing rubber ducks that were confiscated from migrants.

"One of the things I think these photographs remind us of is that even small injustices can be the first step on a path towards things that are totally inhumane," said curator Laura Mart.

"It may seem like not a big deal to take away somebody's shoelaces or to take away somebody's toothbrush," she said.

"But when you start doing that, it makes you accept that treating people that way is OK -- then before you know it, it leads to things like children separation."

Tough border controls are a focus of President Donald Trump's re-election campaign.

A Trump administration "zero tolerance" policy launched in 2018 saw thousands of children separated from their parents at the border, a tactic apparently meant to frighten the families, before the government backed down amid a torrent of criticism.

Tough border controls are a focus of President Donald Trump's re-election campaign.

Mart highlighted a photograph of rubber ducks, some caked in mud -- a seemingly sentimental choice, but with a pragmatic purpose.

Kiefer went through the trash to collect thousands of items seized by border agents from migrants and asylum seekers.

"Rubber ducks were used to mark the trail," she explained.

"They were used for navigation so that groups of migrants can find their way through the cactus and through the brush."

Agence France-Presse