For those desperate souls who would sneak across this frontier, consider the obstacles: armed bandits. A river, low this time of year but still populated by crocodiles and man-mauling hippos. Multiple rows of fences watched by zealous border guards. And all along, the goal is to enter a country that's dangerously hostile to immigrants.
Yet to escape President Robert Mugabe's Zimbabwe, the risks increasingly appear to be worth taking.
One of the largest illegal migrations in the world continues to swell as Zimbabweans stream into South Africa, fleeing a brutal crackdown by Mugabe in the run-up to last month's presidential election. Zimbabwe's main opposition party says that security forces and government militias have killed more than 100 of its members and abused or tortured thousands of others.
Three weeks after the election, which Mugabe won by default when his opponent withdrew because of the violence, hundreds of political activists remain in jail. Mugabe's militias haven't been disarmed.
A decade-long economic collapse already had emptied Zimbabwe of nearly a third of its people, but human rights groups say that the election attacks accelerated the flight into South Africa. Every week, soldiers and police arrest dozens, sometimes hundreds, of illegal migrants near the main border crossing outside the town of Musina. Authorities say that more sneak across undetected.
The influx is putting more pressure on South Africa, the continent's most prosperous nation but one that views its estimated 5 million African immigrants – who form more than one-tenth of the population – with a volatile mixture of fear and resentment. In May, more than 60 were killed in anti-immigrant violence.
Most of the immigrants – some say as many as 3 million – come from Zimbabwe, the vast majority of them undocumented. In recent weeks, thousands have arrived in Johannesburg, South Africa's economic capital. Hungry and destitute, they're passing the coldest nights of the year in public parks, on street corners and in churches.
“I'm very alarmed at the increase,” said Paul Verryn, bishop of the Central Methodist Church in Johannesburg, which has sheltered refugees for two decades. These days more than 2,000 Zimbabweans – teachers, doctors, laborers, students, mothers and their infant children – fill every room in the church, spilling into the stairwells and onto the pavement outside.
“The church has never received as many people as we are on a daily basis,” Verryn said.
Among them is 29-year-old Tendai Mundoza, who jumped the border with her family last month after government militias badly beat her husband, an opposition supporter, outside their home in the Zimbabwean capital of Harare. Her teenage brother was abducted before the election and hasn't been heard from.
To make the crossing, the family scrounged together 5,000 South African rand, about $650. After surrendering half of it to Zimbabwean bandits who patrol the border, crossing a dry patch over the Limpopo River and spending the rest of the money to bribe their way past South African police, Mundoza now sleeps alongside her two young children in a room crowded with more than 50 others.
“It's very difficult here,” she said as her 10-month-old dozed on the thin cotton blanket that serves as the family bed. “It's too congested. The children become sick. But we can't go back home.”
The destination for most illegal crossings is Musina, which has the gritty feel of border towns in the U.S. White police vans roam the streets after dark while young migrants huddle under the dim lights of bus stops, waiting for rides south.
One recent night, along the busy Johannesburg highway, a half-dozen disheveled young men emerged from the bushes behind a truck stop. Wordlessly, they filled bottles with water from a hose next to a gas pump and gulped the water like camels. Then they trudged off to the side of the highway, where one of them pointed his right forefinger into the dark sky, the signal for a lift to Johannesburg.