(CNN) Apprehensions of migrants on the southern border have reached levels not seen in more than a decade. The sharp uptick has spurred a mix of finger pointing in Washington.

Trump administration officials say the skyrocketing numbers are more proof for the case they've been making for months: Loopholes in the US immigration system , they say, are incentivizing a growing number of migrants to come and sparking a dramatic change in who's making the journey.

Democrats argue the administration itself is to blame and that its policies have exacerbated the crisis.

Meanwhile, there's a significant shift in who officials are taking into custody. Overcrowded Border Patrol facilities are packed not with the single men from Mexico who once made up the majority of border-crossers -- but primarily with Central American families and unaccompanied children.

North of the US-Mexico border, the political sparring continues. South of the border, the reality on the ground is more complicated.

But policy experts and officials have found some common ground. A confluence of events, they say -- including harsh conditions in Central America, US policies, lack of political will in the US and more sophisticated smuggling efforts -- led to the highest number of apprehensions on the US-Mexico border in 13 years.

How government policies fuel migration

A complex "cauldron" of factors are coming together, says Andrew Selee, president of the nonpartisan Migration Policy Institute. And US policies have played a notable role in influencing what's happening at the border.

"This crisis is the creation, yes, of bad conditions that have been there for a long time, but also policymakers who have been unable or unwilling to make policy choices," he says. "That, I think, is at the heart of this."

Selee says two major factors have fueled the increasing numbers: 1) A growing awareness in Central America that immigrant families who make it to the U.S. aren't being detained in large numbers -- or deported and 2) A major push from smugglers in the region to offer more options to would-be migrants.

"The smuggling business became quite sophisticated as a result of competition from the caravans," Selee says. "They started offering different price models. They started offering different bus trips. They started offering financing."

And the highly publicized rollback of the Trump administration's family separations policy had an unintended consequence, Selee says.

"Family separation and to a lesser extent some other measures that the Trump administration pursued put Central American families on notice that the US doesn't detain families," he says.

In addition, he says, the Mexican government's efforts earlier this year to provide documents legalizing more migrants who arrived in Mexican territory may have incentivized some to make the journey.

"It's a snowball effect. There's not one cause. ... But I think it's hard to figure out how you stop that. It gains a momentum of its own which becomes much harder to stop."

U.S. Border Patrol Chief Carla Provost told CNN Thursday that there are "numerous factors" pushing Central Americans to leave their countries. One major driver, she said: Smugglers are reportedly telling families they'll be released if they come with children.

"We have apprehended over 230,000 children being brought into the country illegally this year already. That's unprecedented in numbers."

But Selee and other experts note that US policies are only part of why people risk the dangerous journey north.

Drought, poverty and violence in Central America

It's notable, Selee says, that while the number of Guatemalan and Honduran immigrants coming to the US has increased significantly, the number of Salvadoran and Mexican immigrants hasn't.

"That does tell you there's something different about circumstances on the ground in Guatemala and Honduras," Selee says. "Long-term effects of drought, long-term effects of violence, and then more short-term effects of a political system that's increasingly chaotic in both countries."

Migrants aren't listening to messages from the White House or any other government officials, says Pedro Pablo Solares, who writes a column on migration for Guatemala's "Prensa Libre" newspaper. They're hearing directly from people they know who've made the journey -- and still remain in the United States.

"Their only source of information, the truth that is very present for them, is what their neighbors who left last month are saying," Solares says. "If the experience were negative, the majority wouldn't do it."

Meanwhile, drought and famine are hitting farmers hard, Solares says. And regions of Guatemala -- particularly some indigenous communities where people rarely migrated before -- are seeing a dramatic change.

"We've seen a drastic, exponential increase in migration," Solares says.

In one town, Solares said he recently interviewed teachers who said 20 students from one small school left this year to migrate to the US. Last year, only one student had gone. Before that, they'd never seen a student leave.

"The decision for them becomes a no-brainer," Solares says. "It's an option of life, while they're facing the option of death in their communities."