ASSAMAKA, Niger (AP) — On the map, it links Algeria's Mediterranean coast to the distant Atlantic shore in Nigeria. Along the way, however, the Trans-Sahara highway frequently deteriorates from black tar into sand tracks lined by half-buried tires.

Once a well-worn roadway for overlander tourists, the highway's 4,500 kilometers (2,800 miles) are a favored path for migrants heading north in hopes of a better life — and more recently, thousands who are being expelled south from Algeria. They travel in temperatures reaching 48 degrees Celsius (118 degrees Fahrenheit) in summer.

In Niger, the 450 kilometers (280 miles) linking Agadez to the northern border settlement of Assamaka are largely a fiction of mapping. Harsh desert conditions and increased insecurity have rendered construction and maintenance close to impossible.

The grand monotony of the bare Tenere desert is broken by the carcasses of abandoned vehicles, lone trees able to survive on the barest whisper of water, rusted water barrels and sand-swept truck tires used as distance markers.

There are nonetheless signs of life: a gas pump outside Arlit, a power line bringing electricity to nearby uranium mines, a herdsman and the ubiquitous camel, which thrives where most fear to tread.

The frame of an abandoned Peugeot 404 rests in Niger's Tenere desert region on June 3, 2018. (AP Photo/Jerome Delay)

A sandal lies on the ground in Niger's Tenere desert region on June 3, 2018. (AP Photo/Jerome Delay)

A Nigerian army pickup drives Niger's Tenere desert region on June 3, 2018. (AP Photo/Jerome Delay)

A bullet-ridden barrel indicates the direction of Arlit on June 3, 2018. (AP Photo/Jerome Delay)

A transmission tower stands in Niger's Tenere desert region of the south central Sahara on Wednesday, May 30, 2018. It brings electricity to nearby uranium mines. (AP Photo/Jerome Delay)

A tire used as a road marker hangs from a tree in Niger's Tenere desert region on June 3, 2018. (AP Photo/Jerome Delay)

A man and his donkey transport water barrels towards the Algerian border in Niger's Tenere desert region on June 3, 2018. (AP Photo/Jerome Delay)

A dead goat lays in the sand outside the Assamaka border post in Niger's Tenere desert region of the south central Sahara on Sunday, June 3, 2018. Travelling in temperatures reaching 48 degrees Celsius (118 degrees Fahrenheit) in summer, the grand monotony of the bare Tenere desert is broken by the carcasses of abandoned vehicles, lone trees able to survive on the barest whisper of water, rusted water barrels and sand-swept truck tires used as distance markers. (AP Photo/Jerome Delay)

A truck carrying goods and migrants drives through Niger's Tenere desert region of the south central Sahara on June 3, 2018. (AP Photo/Jerome Delay)

A gas pump stands in Arlit, the last major settlement in Niger's Tenere desert region on May 31, 2018. (AP Photo/Jerome Delay)

A man stands by his hut in Niger's Tenere desert region on May 30, 2018. (AP Photo/Jerome Delay)