Welcome to the latest installment of “The Consequences,” a series of chats about the issues being debated in this year’s political campaign. Throughout the campaign, we’ll gather a group of FiveThirtyEight staffers and guests for a conversation on subjects in the news, particularly when the subjects are complex and could use a little illumination.

This week’s subject is immigration, which is a central theme in this year’s presidential race. Our participants are three members of FiveThirtyEight’s staff — the site’s economics editor, Ben Casselman, and two reporters who write frequently about immigration and economic issues, Farai Chideya and Anna Maria Barry-Jester — and one guest, Ana Gonzalez-Barrera. She is a senior researcher at the Pew Research Center who has studied statistics and public-opinion polling on immigration.

Ben: Thanks to you all for joining us! Immigration is maybe THE issue of the 2016 campaign, at least for Donald Trump. And it was right back center-stage Wednesday when Trump made a surprise trip to Mexico and then delivered a major speech in Phoenix that outlined his immigration policy. So we have lots to talk about.

Before we get into the policy details too much, though, I want to start with some basic facts about immigration and illegal immigration. Ana, maybe you can start us off here: What are the basic trends on immigration in general and illegal immigration in particular? The two look pretty different, right?

Ana: There are 42.2 million immigrants living in the U.S., according to 2014 census data. Of them, an estimated 11.3 million were in the country without authorization. This number is slightly down from a 12.2 million peak in 2007, right before the Great Recession.

Ben: Right. One thing that often seems to get lost in this debate is that the trends on legal and illegal immigration look very different. The total number of immigrants is rising and is on track to hit an all-time high as a share of the population. But the number of undocumented immigrants is down from its peak and has been pretty much flat in recent years.

Ana: That is correct. And it is mostly driven by a shift in the countries where most immigrants are coming from nowadays — from Mexico and Latin America in general to Asia, particularly China and India.

Ben: Right. This chart always sort of blows me away.

Farai: One thing worth noting about that pattern, Ben, is that the idea of people returning to their home countries voluntarily when they don’t have legal status, or in political language “self-deporting,” has been on the rise. And even Mexican-Americans with legal status have been returning, partly as a function of the economy in the past decade.

Ben: And the number of U.S. residents born in Mexico has been falling somewhat in recent years.

Ana: Right. After reaching a peak in 2007, the number of Mexican immigrants living in the U.S. has dropped off. And between 2009 and 2014, there were more Mexican nationals leaving the U.S. for Mexico than there were Mexican immigrants coming into the U.S. Most of that is due to a 1 million-person decrease in the number of unauthorized immigrants from Mexico from 2007 to 2014.

Farai: In Trump’s immigration speech in Phoenix, he said that returning to one’s home country was the only path to citizenship, something that has been hotly debated as bipartisan immigration reform has failed to find traction for years.

Ben: I want to keep this conversation focused on policy, but a bit of political context might be helpful here. If the number of undocumented immigrants is flat or falling and the wave of Mexican immigrants has already crested, why is this such a big issue this year? Is it mostly about economics? Culture?

Anna: That’s a great question, Ben. The net loss of Mexican immigrants doesn’t seem to be well understood by the public and certainly isn’t what we hear in the presidential debates, particularly from the Trump campaign (though Mexican President Enrique Peña Nieto did bring it up in the press conference after his meeting with Trump on Wednesday).

Ben: I’ve written before about how our immigration debate seems stuck in the 1990s, “Prop. 187” era.

Farai: Ben, in brief, I think both economics and culture. Gallup did 87,000 surveys between July 2015 and July 2016, and among other things, the research found that proximity to the Mexican border decreased the chances of someone being a Trump supporter. In the speech — and I know we are focusing on policy, but this is worth noting — there were many references to assimilation and culture. This is similar to some of the research done in the U.K. during the Brexit vote on how appeals to keeping English culture intact resonated.

Ben: Let’s stay on culture for a second. Is there any data around whether immigrants from Mexico have assimilated more slowly (or more quickly) than past generations of immigrants? I know Pew has done some polling on this and has found that Americans don’t think immigrants are assimilating quickly enough. On the other hand, a substantial majority of U.S. Hispanics speak English. Especially second- and third-generation Hispanics.

Farai: This 2013 study found that Latino families learn English more quickly than 19th-century immigrants from Germany did. In both cases — Germans in the 1800s, in cities like my hometown of Baltimore; and some Mexican-American and Latino communities today — there were and are communities with a dominant non-English language. Just one measure.

Ana: The adoption of English as the primary language among Hispanics just takes a couple of generations. By the third generation, almost all Hispanics speak English very well, and most use English as their primary language.

Anna: Language is one measure of assimilation. There have been efforts to make more robust calculations, including measures like civic participation, marriage, homeownership, economics. But assimilation isn’t an easy thing to measure; it means different things to different people.

Ben: So let’s turn to a topic that seems to be at least an undercurrent of a lot of this debate and that Trump emphasized in his speech: crime and security. Trump brought out a group of parents whose children had been killed by undocumented immigrants. But what do we actually know about illegal immigration and violent crime?

Ana: In our surveys, we have found that immigration, terrorism and crime are much more salient issues among Trump supporters than among Hillary Clinton’s.

Ben: And yet studies pretty consistently show that immigrants, including undocumented immigrants, have a LOWER rate of violent crime than native-born Americans. (That link is from a conservative writer on the WSJ op-ed page, by the way.)

Farai: This article from The Washington Post cites several studies, including one from Pew, showing that crime among immigrants is lower than among native-born Americans.

Anna: One thing that was striking to me last night was that crime related to unauthorized immigration and questions about vetting Syrian refugees were lumped together at times. These are groups who enter the country in very different ways.

Ben: Right. If you come here illegally and planning to work (as most immigrants do), then you have a strong incentive not to commit crimes — if you get caught, you can be deported! But, of course, the concern about terrorism is that someone could come here planning to commit a violent act. Claiming refugee status, though, is perhaps the most difficult way to enter the country — it isn’t clear that potential terrorists would choose that method.

Farai: It’s worth noting that in 2015, nearly 60 percent of removals by U.S. Immigration and Customs Enforcement officials were of people with criminal backgrounds. That seems to indicate an ongoing enforcement priority.

Anna: And the share of removals that are people with criminal backgrounds has increased over time.

Ana: The Obama administration has focused its efforts on deporting immigrants with criminal convictions and those who have recently crossed the border. In the last two years, that focus on criminal convicts has actually shifted from any type of conviction to more serious crimes.

Ben: To the extent there was any “pivot” in Trump’s speech, it was away from pledging to deport all 11 million undocumented immigrants and toward deporting those who commit crimes. But isn’t that pretty close to existing policy?

Anna: Ben, he did talk about bringing back the Secure Communities program, which has been criticized as targeting people who had any interaction with the criminal justice system, rather than focusing on people who have committed crimes. That was a program the Obama administration discontinued in 2014.

Ben: Let’s stay on this for a moment. The idea behind Obama’s DACA (“Deferred Action for Childhood Arrivals”) policy was basically: “Look, we can’t deport everyone, so we already set priorities. Let’s just formalize that system and grant some sort of legal status to people we probably wouldn’t have deported anyway.” Trump’s rhetoric is very, very different, of course. But policy-wise, he seems to want to go back to Obama’s first-term policy of deporting undocumented immigrants convicted of crimes (violent or otherwise) while not granting any formal status to others. So in that sense, isn’t this more or less the standard GOP line on immigration?

Anna: To the extent that there is a GOP standard, Ben, perhaps. But there appears to be an age divide among Republicans in how they think about immigration.

Ben: How so?

Anna: Younger Republicans tend to support a path to citizenship, according to some surveys. And there was a moment when immigration reform seemed to have enough bipartisan support. In the wake of the last presidential election, when immigration wasn’t being used for campaigning, it was still contentious, but there was a lot more support for the idea that you can’t just do nothing for the groups that aren’t being targeted for deportation.

Farai: But it’s also worth remembering that it’s an older GOP that showed an enthusiasm for amnesty. Ronald Reagan signed the 1986 Immigration Reform and Control Act, on this list of the 10 most important pieces of legislation shaping immigration policy.

Anna: That’s a great point, Farai.

Farai: I think this election has exposed many divides, and one of them may be between younger GOP voters and their party leadership in Congress on issues like this.

Ben: One place Trump does seem to depart from GOP orthodoxy is on legal immigration. He talked about wanting to cap immigrants as a share of the population, to keep it “within historical norms.” It’s true that the immigrant population is high by historical standards, right, Ana? And on track to set a record somewhere in the middle of this century?

Ana: That is correct. Every year we are breaking records in the number of immigrants living in the U.S. Though as a share of the population, it is at the same levels from late 19th- and early 20th-century waves. But the share is projected to keep increasing and reach record highs in the coming decades.

Ben: Of course, one reason that immigrants are rising as a share of the population is that native-born Americans aren’t having as many children as they used to. Immigration is a big reason that the U.S. is in better demographic shape than places like Japan or parts of Europe.

Anna: Right, Ben. Several countries in Europe have been struggling with this, where they either need more babies or more immigrants to avoid an economic crisis.

Farai: There are a lot of studies looking at the financial impact of undocumented immigrants. This, however, really caught my eye: “The Social Security Administration estimates that in 2010 illegal immigrants paid a net contribution of $12 billion, either by working under a fraudulent Social Security number or by using a legitimate Social Security number after overstaying a visa or otherwise losing permission to work.”

Ben: OK, so staying on economics: Immigrants raise the working-age share of the population. They’re paying into a Social Security system that they can’t draw from. And research is pretty consistent in saying that immigration is a net benefit for the economy. Yet Trump talked a lot about immigrants taking jobs, displacing American workers. What’s behind that disconnect?

Anna: Is there some research on whether low-skilled undocumented workers hurt wages for the native-born? Is there consensus on that?

Ana: In a recent survey, we found that a majority of the U.S. public does not believe that immigrants mostly fill jobs U.S. citizens would like, and that includes Trump supporters.

Farai: There are some analyses, including one published in the Southern Economic Journal and cited in this Forbes article, that argue there is a virtuous circle where less English-proficient laborers and less skilled immigrants take some jobs and better English speakers take others. But I also know from my field reporting that in economic downturns like the Great Recession, unemployment in areas with large numbers of migrant workers — documented and undocumented — can become extreme. In 2010, unemployment rose to 30 percent in Yuma, Arizona, which is at the border of both California and Mexico. Whether or not that was directly attributable to the migrant labor, many people blamed the workers.

Ben: So this is a very active debate in economics right now. As I said, there’s a lot of agreement that immigration is a net benefit to the economy, in terms of its impact on GDP. But there’s much less agreement on the impact that low-skilled immigration has on low-skilled American workers. There has been a flurry of papers recently on the evidence from the Mariel boatlift, which brought a huge wave of mostly low-skilled Cuban workers to Miami in 1980. A famous study by David Card found that the boatlift had basically no effect on the wages of native-born workers. But more recently, Harvard economist (and immigration critic) George Borjas has re-evaluated the evidence and found that the influx did hurt native-born wages. Borjas and his critics have been going back and forth ever since.

This has some similarity to the trade discussion we had a couple of months ago, where trade is good for the economy but not necessarily good for all workers. Ana, what do we know about the undocumented population in terms of their skills and education level?

Ana: Overall, the unauthorized immigrant population tends to have a lower level of educational attainment and job skills. They are highly concentrated in certain industries like construction, food preparation, hospitality and farming.

Anna: And the predominant industries are somewhat regional, right?

Ana: Some of them are, not all.

Ben: What about the impact of skilled immigration? Trump indicated that he wanted to grant visas based on “merit, skill and proficiency.” But there have been concerns lately about companies bringing in skilled workers from India and elsewhere when they could be hiring U.S. workers, right?

Farai: Ben, this is a huge difference between Trump and Clinton. The tech industry, for example, has not been enthusiastic about Trump, based on his opposition to raising H-1B visa limits.

Anna: This has been a big conversation in science and technology fields, Ben.

Ben: Explain that a bit more. What’s the H1-B debate in a nutshell?

Farai: The H-1B visa is used to bring in skilled workers, many of whom end up in the U.S. as computer programmers or in other high-tech jobs. It’s only supposed to be used when there are not U.S. workers available. But there have been a variety of lawsuits and allegations that U.S. employees have been asked or forced to train H-1B workers to take their jobs.

Ben: So, we’re nearing the end of our time here, and somehow we’ve failed to mention THE WALL. Which apparently is going to be “impenetrable, physical, tall, powerful, beautiful” according to Trump. So first of all, how many undocumented workers get here by crossing the border illegally? And has that number been rising or falling?

Ana: Our latest estimate is that 60 percent of all unauthorized immigrants came here illegally; the rest overstayed their visas. But as the number of apprehensions at the border has decreased in the last decade, it is likely that that share has gone down.

Ben: One thing Trump spent a lot of time on in his Phoenix speech was the need for a better system to track people who overstay their visas. That’s something that Congress has actually mandated, right? Why don’t we have that system already?

Anna: This is such an interesting issue, Ben! A couple of general thoughts: it’s not that easy to track people, and it goes against our ethos about surveillance in the U.S.

Ben: By the way, do you know who are the worst offenders when it comes to overstaying visas? (At least in raw numbers.) Canadians.

Farai: There is a biometric entry system (after seven different laws have been passed) but not an exit system. I agree with Anna about American privacy concerns being an issue with implementation.

Anna: But also there are some strange logistical issues with the biometric entry system. Our airports take biometric information from people traveling internationally, but not domestically. We would have to redesign our airports in order to track at airports, at least.

Ben: We need to wrap up here, but let me take a step back here before we do. The one thing that everyone seems to agree with is that our current immigration system is broken. What’s broken about it? And are there any areas where there’s enough agreement that we might see movement after the election?

Farai: Well, I return to a bit of politics. Donald Trump said in Arizona that America’s top priority should be U.S. citizens, not the millions of undocumented workers living here. There has not been a resolution among the public whether legalizing or naturalizing undocumented immigrants is in the interest of U.S. citizens. I say that only to note that while we deal in facts and data here, people also deal in imagery and emotion. Some of the questions you asked have room for debate; others seem clear-cut. But without a political will, there will not be a resolution.

Anna: I think that’s key, Farai. This isn’t a question that gets answered with data, as you said. There has been a lot of agreement in recent years around undocumented people who came to the U.S. as children. It seems like there has been some support for the DACA program, and I’d expect that to continue to be formalized in law, at least in some states, as well as federally.

Ben: “Not a question that gets answered with data”? Does. Not. Compute.

Kidding, of course. But, Ana, as a last word here — is there one thing that you wish more Americans knew about immigration?

Ana: I guess the basic facts — that while the immigrant population keeps increasing, the number of unauthorized immigrants has leveled off. And also that immigration from Mexico is no longer at the levels that it was one or two decades ago.

Ben: It would definitely be nice to see a few more facts in this debate, even if they wouldn’t resolve the issues altogether. So thanks to all three of you for helping to provide them. It’s been a really interesting conversation.