Cartels have long been in the business of facilitating the illegal entry of aliens into the U.S.  But the coyotes have discovered a way to drastically lower their overhead costs while maximizing profit.

It's called the "conveyor belt" system, where the cartels use buses to bring Central American asylum-seekers through Mexico right to the U.S. border.  They then walk across the border and turn themselves in to border patrol officers as they seek asylum.  This is a massive abuse of U.S. asylum laws, but it is tolerated by the courts, as well as Republicans and Democrats.

Washington Post:

Paying up to $7,000 per adult with child, families are transported to staging areas at ranches and hotels in southern Mexico, where they are organized into bus groups and rushed north along Mexican highways, "stopping only for food, fuel and bathroom breaks," according to the U.S. law enforcement documents. ...

Within 72 hours of leaving the staging areas, the buses arrive at predetermined drop-off points within walking distance of the U.S. border.  Migrant families are clustered into groups that have at times exceeded 300 adults and children, and they walk directly across the border, in some cases stepping over barriers in long, orderly lines.  They then surrender to U.S. Border Patrol agents and initiate asylum claims. ...

By using the direct-bus method, smugglers can eliminate the need for stash houses along the border where they would normally keep migrants under the watch of armed guards before sneaking them across the border.  The express routes "minimize overhead and maximize capacity," according to the U.S. documents, allowing smugglers to reduce "operational costs to a minimum."

Brietbart's Neil Munro lists some of the loopholes that allow this practice:

The judges' loopholes, for example, require border officials to quickly release migrants who bring their children with them across the border.  The resulting catch-and-release policy allows the migrants to get through the border wall and into U.S. jobs in one day.

Judges have also moved quickly to block any countermeasures by the U.S. government.  For example, a revision of "credible fear" asylum rules set by former Attorney Gen. Jeff Sessions was blocked nationwide by a judge even before a trial.  The block ensures that nearly all migrants can get released into the United States by merely asking for asylum, regardless of whether they have grounds for seeking asylum.

Similarly, GOP and Democratic politicians have done little to slow the rapid growth in migrants.  In fact, the February budget deal provides hundreds of millions of dollars in aid, transportation, and welfare for migrants as they cross the border.  The budget deal also reduces the number of jail spaces where migrants can be kept until their asylum claims are heard.

Most of the migrants are not schooled in the ins and outs of U.S. asylum laws, so someone is teaching them how to game the system.  Otherwise, it's the same old story: while waiting for their court hearing on asylum, a wait that lasts years, the migrants disappear into the U.S. heartland and work illegally. 

Outside jawboning the Mexican government, very little is done to halt this massive flow of migrants.  It's estimated that up to one million Central Americans will enter the U.S. this way this year.  That's an intolerable burden on local governments, who are forced to feed, school, and care for the newcomers for years.

Sending asylum-seekers back across the border to wait in Mexico is an option, but the Mexican government allows only a certain number back into their country.  More pressure must be placed on Mexico to halt this human-trafficking instead of turning a blind eye to the "conveyor belt."