Migration is not a project for the destitute or desperate. Human smugglers charge $3,500–$7,000 a person to convey a would-be asylum seeker from Central America to the United States. The trip from Africa costs much more. Some Congolese migrants, interviewed by The New York Times, began by traveling overland to Angola. From that country, they flew across the Atlantic and South America to Ecuador. Then they continued by bus and foot northward thousands of miles across Colombia, Central America, and Mexico to Texas.

How do they afford the journey? There are as many different answers to that question as there are migrants. Here’s the story of the Punjabi family that lost their daughter in the Arizona desert. The father, known as A. Singh, made his way to the United States in 2013. He filed an asylum petition. This was not a promising plan. In 2013, U.S. courts rejected 97 percent of asylum requests filed by Indian citizens.

But after rejection, there’s appeal. If you lose on appeal, you can just stop showing up. The authorities are unlikely to find you, and even if they do, they are unlikely to send you home. Six years later, A. Singh is still in the United States, his asylum case still unresolved. Along the way, he accumulated enough money to send for his wife and daughter. They traveled from India to Mexico, and were then met by smugglers who led them part of the way along the border—and then abandoned them without water in the scorching June desert heat.

Migrant children usually follow adults who have made the journey ahead of them. Warren Binford, a law professor at Willamette University, visited a Clint, Texas, detention facility earlier this month. In a June 21 PBS interview, Binford told Judy Woodruff, “Almost every child that I interviewed had family, parents, uncles, aunts, grandparents, siblings here in the United States who are waiting for them and are ready to care for them.”

Migration is a networked process. As a migrant diaspora expands, it can accumulate resources to enable more relatives to follow—many of them escaping desperate circumstances, in search of a better future. Those resources include not only the cash necessary to pay the smugglers, but also the sophisticated local understanding that enables asylum seekers to settle more easily. It’s tough to be the first Congolese asylum seeker to arrive in Portland, Maine (the city in which 300 Congolese asylum seekers have recently arrived). It will be easier to be the 300th, and it will be easier than that to be the 3,000th. Their predecessors will help them find places to live and work, and show them how to navigate the bureaucracy that will process their cases.

This network effect may help explain a paradox that would seem otherwise mystifying: Why is migration from Central America surging even as the crimes that supposedly motivate the migration are plunging?