Migration between countries concentrates into a limited number of corridors rather than distributing according to wage differences. The pattern is driven by networks, and it persists long after the original reason for a route has faded.
Networks lower the cost of moving
A person moving to a place where relatives or people from their community already live has help finding housing, work and official assistance.
That reduces both the financial cost and the risk of the move, which matters more than a marginal difference in wages between destinations.
Each arrival strengthens the network, making the next move easier still, which is why corridors deepen over time rather than dispersing.
Historical ties establish the first path
Corridors frequently originate in colonial relationships, labour recruitment agreements or shared language, all of which lower the initial barrier.
Once established, the route outlives its cause, because the network effect operates independently of whatever created the connection.
This is why migration patterns often look unrelated to current economic conditions and closely related to arrangements made generations earlier.
Information travels along the same channels
Prospective migrants rely on accounts from people they already know, since official information rarely covers the practical questions that determine whether a move succeeds.
That information is detailed and reliable about the specific destination the network occupies, and almost entirely absent about anywhere else.
Decisions are therefore made between a well-understood option and an unknown one, which reinforces the existing corridor almost automatically.
Remittances tie the ends together
Money sent home is a substantial financial flow for many origin communities, and it funds the education and travel costs of subsequent migrants.
The transfer infrastructure develops around established corridors, so sending money along a well-used route is cheaper and easier than along a new one.
These flows create a continuing relationship between the two ends rather than a single departure, which sustains the corridor across decades.
Policy redirects rather than reduces
Restrictions on a particular route tend to change where people attempt to cross and which intermediaries they rely on, more than whether they attempt to move at all.
Diverted routes are typically longer, more expensive and more dangerous, since the safest and most accessible options are the ones closed first.
Legal pathways operate on the same network logic, with family and employer sponsorship channelling movement along paths already established, which is why formal migration also concentrates.