If we measured uninvited immigrants by numbers the U.S. is doing OK compared with Europe. Nevertheless, the spike in the number of children crossing the Southern border is causing some concern among those who are keeping numbers. See What’s Driving the Latest Surge of Illegal Immigration From Central America. They don't answer the question asked in the title. They do say this, however:
But the spikes are causing alarm because crossings of the southwest border had declined after Mexico began better enforcing its borders—with help from the U.S.—and the Obama administration pursued a public awareness campaign in Central America discouraging people from migrating.
The timing is also surprising because peaks in illegal immigration usually occur during the summer, when the weather is more bearable.
“This may be the new normal,” said Marc Rosenblum, the deputy director of the U.S. immigration policy program at the Migration Policy Institute. “Everything that was going on in 2014 that caused people to flee is as bad or worse now. Violence in El Salvador is worse, the whole region is amidst a two-year drought, more families are experiencing food insecurity, there’s political turbulence in Guatemala. Those are strong pressures that will cause people to try to get here.”
President Obama's response to "the new normal" is to open new shelters and add more beds.
The answer to the question of what's driving the surge is that there is no visible opposition to it.