People by the thousands risk crocodile attacks, robbery, drowning and arrest to cross the Limpopo River from Zimbabwe to South Africa, part of a booming migrant economy.
Hundreds of thousands of Palestinians have fled to southern Gaza, but they cannot cross into Egypt because the border is heavily fortified and Cairo is determined to keep it closed.
Some border communities in the U.S. and Mexico are suddenly cut off from each other after a border crossing closed to cope with large numbers of migrants.