Foreign nationals are arrested during a targeted enforcement operation in 2017. (Charles Reed/U.S. Immigrations and Customs Enforcement/AP)

One central promise of Donald Trump’s 2016 presidential campaign was that he would deport immigrants living in the country illegally. At times he would insist that law enforcement officials knew exactly where troublesome immigrants lived — Trump would often claim that he would focus on those with criminal records — and that getting them out of the country would be quick and easy. There were signs that he planned to go broader, such as his endorsement of Dwight Eisenhower’s mass deportation effort in 1954. As with so many other Trump proposals, though, any specifics came mostly with a shrug.

Last month, it seemed that Trump’s deportation pledge was finally swinging into motion. While the government has deported thousands of people since Trump took office (as did President Barack Obama), Trump announced his intention to oversee a mass raid, arresting and deporting hundreds of people at once. Facing internal opposition and leaks that tipped off potential targets, Trump delayed the plan at the end of June.

According to the New York Times, the raids are back on, scheduled for this weekend.

There’s a lot of misinformation and misunderstanding about the targets of these raids and the undocumented immigrant population more broadly. Most important is who is being targeted and why.

The raids are reported to be targeting 2,000 people scheduled for deportation but could include more people than that. Most of those reported to be targeted have recently arrived in the United States.

The Times report indicates that the focus of the weekend's raids will be 2,000 people — including children — who had been ordered to be deported. In doing so, "authorities might detain immigrants who happened to be on the scene, even though they were not targets of the raids," Caitlin Dickerson and Zolan Kanno-Youngs report.

Those who will be the focus of the raids are people whose immigration proceedings were expedited by the administration in September, meaning that they’re relatively new arrivals to the country. That’s particularly true in the broader context of unauthorized immigration in the United States. About two-thirds of immigrants in the country illegally have been in the country for at least 10 years, according to Pew Research Center, compared with about a fifth who have been in the United States for five years or less.

The deportation orders include people who missed court hearings — that they may not have known about.

Some of those slated for deportation have been targeted for not having attended required court hearings. In some cases, though, the immigrants may not have known they were supposed to.

That those targeted in these raids were part of the expedited process introduced last year is important. David Leopold, an immigration attorney who served as general counsel for the American Immigration Lawyers Association, explained why in an email to The Washington Post:

"Of the group of immigrants with deportation orders there are serious due process concerns because they either didn’t get notice of the hearings or the hearings were held in absentia or were not held at all," Leopold wrote. In other words, many of them "did not have their day in court."

He referred to a report from Syracuse University’s TRAC program, which analyzes immigration-related data including the outcomes of hearings for family groups included in the expedited process. Of those with legal representation, 99.9 percent attended their initial hearings. Among those without legal representation, that figure fell to 81.6 percent. Those who don’t attend a hearing are flagged for deportation.

But that poses a problem.

“Under our current system, there is no legal requirement that immigrants actually receive notice, let alone timely notice, of their hearing,” the TRAC report reads. Some immigrants, it indicates, “may receive a written notice, but the notice may have been in English, which they couldn’t read.” Others may not have complete address information to be contacted for a hearing.

That works in the other direction, too.

“The Border Patrol states that it is quickly releasing families directly ‘with notices to appear in immigration court,’ " the report reads. ”While families may have been handed notices to appear, these notices are unlikely to contain the actual location and time for their court hearing since such details will not yet have been determined."

On some occasions, TRAC found, no hearing was scheduled at all — but immigrant families were still marked as having not attended.

Unfortunately for those immigrants, there’s not much recourse, Leopold explained. Unless there are exceptional circumstances that prevented their appearance or they can document that they gave the government a correct address but still didn’t receive notice, an order can’t be reopened.

Immigrants who have recently arrived in the country and are here illegally have in recent years been more likely to be Asian than Hispanic and mostly overstayed visas.

It’s worth noting that a focus on immigrants who have crossed the border into the United States without documentation or who have come into the United States across the Mexican border seeking asylum doesn’t address the most common new arrivals in the unauthorized immigrants population in recent years.

Pew analysis finds that in most years over the past decade, there have been more Asian than Hispanic immigrants who arrive in the United States and stay without documentation. That has probably shifted given the recent increase in arrivals at the southern border, but in 2017, for each Hispanic who came into the country without authorization, 1.4 people of Asian descent did.

Most of those immigrants probably arrived on valid visas but didn’t leave once the visas expired. Among immigrants from Mexico and the Central American countries of El Salvador, Guatemala and Honduras, this was less likely.

Most immigrants here illegally live in big cities — but three-quarters of immigrants in the United States are here legally.

This weekend’s raids will reportedly focus on 10 large cities. That’s not a surprise; most of the 11 million immigrants in the country without authorization live in large urban areas. (If you’re curious how we can be confident in that 11 million figure, we’ve written about Pew’s estimation process.) Since the recession, that figure has dropped. As of last year, undocumented immigrants made up about 4.8 percent of the country’s workforce.

While most Americans think that the majority of immigrants in the country are here illegally, that’s not the case. In fact, only about a quarter of the immigrant population is estimated to be in the United States without authorization.

If everyone in Guatemala, Honduras and El Salvador moved to the United States, the growth in population would be the same as the increase the United States has seen since about 2005.

One useful bit of additional context. The recent increase in migrants at the border with Mexico are coming from the three Central American countries identified above. The recent surge — which has still been more modest than the monthly norm about 20 years ago — has largely included migrants from those countries.

While there’s been some hand-wringing about the effect of heavy migration from Central America, scale is useful. There are about 16.9 million people in Guatemala. El Salvador is home to about 6.4 million, and Honduras is home to about 9.3 million. In total, that’s a population of 32.6 million.

In 2005, the population of the United States was about 295.5 million. Since, it has climbed to 327.2 million — an increase of 31.7 million.

In other words, suddenly dropping the entire populations of all three countries into Kansas would mean a shift in the country’s population about the same as the increase since “The Apprentice” first came on the air.