The Mexico – United States barrier – also known in the United States as the border fence, rotted fence or border wall – is actually several separation barriers designed to prevent illegal movement across the Mexico – United States border.

Indonesian mahouts (elephant masters) bathe elephants prior to a daily patrol at a Conservation Respons Unite (CRU) to control elephant-human conflicts in Serbajadi, East Aceh on April 7, 2016. Elephants have joined the front line in the fight against poaching and illegal logging in the dense jungles of Sumatra. Guided by their Indonesian mahouts, they trek alongside rivers, over rough terrain and deep into the rainforest in an area that is home to numerous endangered species, from orangutans to tigers, but which has suffered devastating deforestation in recent years. (Photo by AFP Photo/Januar)

Indonesian mahouts clean their Sumatran elephant in a river near the zoo in Medan, North Sumatra, Indonesia, 12 December 2014. According media reports, the smallest of the Asian elephants, Sumatran elephant (Elephas maximus sumatrensis) is facing serious pressures arising from illegal logging and associated habitat loss and fragmentation in Indonesia. The population has come under increasing threat from rapid forest conversion to plantations. (Photo by Dedi Sahputra/EPA)

In this May 4, 2014 photo, a miner holds an amalgam of mercury and gold he mined after working a 28-hour shift at an illegal gold mining process, in La Pampa, in Peru's Madre de Dios region. Thousands of artisanal gold miners sweat through the long shifts and endure, for a few grams of gold, the perils of collapsing earth, limb-crushing machinery and the toxic mercury used to bind gold flecks. (Photo by Rodrigo Abd/AP Photo)

In this Friday, January 7, 2011 photo, people carry baskets of coal scavenged illegally at an open-cast mine in the village of Bokapahari in the eastern Indian state of Jharkhand where a community of coal scavengers live and work. The world's biggest coal users – China, the United States and India – have boosted coal mining in 2017, in an abrupt departure from last year's record global decline for the heavily polluting fuel and a setback to efforts to rein in climate change emissions. (Photo by Kevin Frayer/AP Photo)

Women stage a topless protest in Buenos Aires, Argentina on February 7, 2017. Activists take to streets of downtown after three women had been topless sunbathing on Necochea, near Buenos Aires, when they were approached by officers that told to cover their breasts. The sunbathers and officers argue, with the girls insisting going topless is not illegal, but the police insist they are offending the local culture. This protest is in support of the three women of Necochea. (Photo by Claudio Santisteban/ZUMA Wire/Rex Features/Shutterstock)

Ebiowei, 48, carries an empty oil container on his head to a place where it would be filled with refined fuel at an illegal refinery site near river Nun in Nigeria's oil state of Bayelsa November 27, 2012. Locals in the industry say workers can earn $50 to $60 a day. Thousands of people in Nigeria engage in a practice known locally as “oil bunkering” – hacking into pipelines to steal crude then refining it or selling it abroad. The practice, which leaves oil spewing from pipelines for miles around, managed to lift around a fifth of Nigeria's two million barrel a day production last year according to the finance ministry. (Photo by Akintunde Akinleye/Reuters)

Two baby orangutans play with each other at the wildlife department in Kuala Lumpur, Malayasia, October 19, 2015. The Malaysian wildlife department in July seized two baby Sumatran orangutans, found in duffel bags, from traffickers who were attempting to sell them to buyers in Malaysia. According to local media, the orangutans will be returned to Medan, Indonesia on Tuesday. The illegal wildlife trade is estimated to be $8 billion a year worldwide, according to TRAFFIC, a wildlife trade monitoring network. (Photo by Olivia Harris/Reuters)