That area is not a border now. It is not even a sieve. It is just an area where people live where ever it is convenient. They flow back and forth across the river as it suits them.
“That area is not a border now... They flow back and forth across the river as it suits them.”
Saw a video of a fully dressed mariachi band wading across the Rio Grande for a performance. The whole border used to be like that - like crossing the street.