President Trump has frequently called the situation at the southern border with Mexico a crisis and insists that building his long-promised border wall will fix it. Here are some of Mr. Trump’s most common assertions of a crisis, and the reality of what we know about immigrants and the border.

“We can’t have people pouring into our country like they have over the last 10 years.”

THE REALITY Illegal border crossings have been declining for nearly two decades. In 2017, border-crossing apprehensions were at their lowest point since 1971.

Total number of arrests for illegally crossing the Mexican border George H.W. Bush Clinton George W. Bush Obama Trump 1.5 million 1.0 0.5 0 ’90 ’92 ’94 ’96 ’98 ’00 ’02 ’04 ’06 ’08 ’10 ’12 ’14 ’16 ’18 Fiscal year George H.W. Bush Clinton George W. Bush Obama 1.5 million Trump 1.0 0.5 0 ’90 ’00 ’10 Fiscal year Source: U.S. Customs and Border Protection

Undetected illegal border crossings have dropped at an even faster rate, from 851,000 in 2006 to approximately 62,000 in 2016, according to estimates by the Department of Homeland Security.

However, there is one group of migrants that is on the rise: families. A record number of families have tried to cross the border in recent months, overwhelming officials at the border and creating a new kind of humanitarian crisis.

Number of arrests for illegally crossing the Mexican border 30,000 Nov. 2018 People with family: 25,172 Others: 21,401 20,000 10,000 Unaccompanied children: 5,283 Jan. 2016 July Jan. 2017 July Jan. 2018 July People traveling with family 30,000 Others 20,000 10,000 Unaccompanied children 2016 2017 2018 Source: U.S. Customs and Border Protection

Asylum claims have also jumped, with many migrant families telling officials that they fear returning to their home countries. Seeking asylum is one way to legally migrate to the United States, but only 21 percent of asylum claims were granted in 2018, and many cases can take years to be resolved.

“Every week, 300 of our citizens are killed by heroin alone, 90 percent of which floods across from our southern border.”

THE REALITY It is true that the majority of heroin enters the United States through the southern border, according to the Drug Enforcement Administration. But the D.E.A. also says that most heroin is brought into the country in vehicles entering through legal border crossings, not through the areas where walls are proposed or already exist.

Most drugs are seized at ports of entry, not along the open border DRUG SEIZURES: AT PORTS OF ENTRY BETWEEN PORTS OF ENTRY Heroin 90% 10% Cocaine 88% 12% Methamphetamine 87% 13% Fentanyl 80% 20% Marijuana 39% 61% DRUG SEIZURES: AT PORTS OF ENTRY BETWEEN PORTS OF ENTRY 90% 10% Heroin 88% 12% Cocaine 87% 13% Methamphetamine 80% 20% Fentanyl 39% 61% Marijuana Source: U.S. Customs and Border Protection | Note: The chart shows drug seizures at all borders, not just the border with Mexico. The southern border is the primary entry point for cocaine, heroin and methamphetamine.

There are more than two dozen ports of entry along the southern border. Barriers are already present in Border Patrol sectors with the highest volumes of heroin seizures.

Heroin seizures in each Border Patrol sector, 2017 Weight in pounds 200 600 1,000 CALIF. U.S. Border Patrol sectors NEW MEXICO ARIZONA El Centro 275 TEXAS El Paso 93 Yuma 223 Tucson 979 San Diego 2,365 Rio Grande 432 Del Rio 154 Big Bend 18 Laredo 503 Ports of entry GULF OF MEXICO PACIFIC OCEAN Existing barriers along the border MEXICO N U.S. Border Patrol sectors CALIF. NEW MEXICO El Centro 275 ARIZONA TEXAS El Paso 93 Yuma 223 Tucson 979 Rio Grande 432 San Diego 2,365 Del Rio 154 Laredo 503 Big Bend 18 Ports of entry GULF OF MEXICO Existing barriers along the border PACIFIC OCEAN MEXICO N U.S. Border Patrol sectors NEW MEXICO TEXAS CALIF. ARIZONA El Centro 275 El Paso 93 Yuma 223 Del Rio 154 Tucson 979 Laredo 503 Big Bend 18 San Diego 2,365 Ports of entry Existing barriers along the border N Rio Grande 432 MEXICO PACIFIC OCEAN NEW MEXICO CALIF. ARIZONA TEXAS 2 5 3 1 4 7 6 8 Existing barriers along the border Ports of entry N 9 MEXICO PACIFIC OCEAN San Diego, 2,365 Big Bend, 18 1 6 El Centro, 275 Del Rio, 154 2 7 Yuma, 223 Laredo, 503 3 8 Tucson, 979 Rio Grande, 432 4 9 El Paso, 93 5 Source: U.S. Customs and Border Protection (seizures data); Reveal from The Center for Investigative Reporting and OpenStreetMap contributors (border barriers)

“Over the years, thousands of Americans have been brutally killed by those who illegally entered our country, and thousands more lives will be lost if we don’t act right now.”

THE REALITY It is difficult to assess the president’s claims that illegal immigration leads to more crime because few law enforcement agencies release crime data that includes immigration status. However, several studies have found no link between immigration and crime, and some have found lower crime rates among immigrants.

Texas, which has the longest border with Mexico and has one of the largest populations of undocumented immigrants of any state, keeps track of immigration status as part of its crime data. The Cato Institute, a libertarian research center, analyzed the Texas data for 2015 and found that the rate of crime among undocumented immigrants was generally lower than among native-born Americans.

Conviction rates are lower for immigrant populations in Texas Number of convictions for every 100,000 residents in each group, 2015 All crime Homicide Sex crime Larceny Native born 1,797 3.1 28.6 267 Undocumented immigrants 899 2.6 26.4 62 Legal immigrants 611 1.0 8.9 74 All crime Homicide Native born 1,797 3.1 Undocumented immigrants 899 2.6 Legal immigrants 611 1.0 Sex crime Larceny Native born 28.6 267 Undocumented immigrants 26.4 62 Legal immigrants 8.9 74 Source: Cato Institute

Some critics of the study argued that the reason undocumented immigrant conviction rates were low was because immigrants were deported after they served their sentences, which prevented them from committing another crime in the United States, reducing their rate of crime relative to native-born Americans.

Alex Nowrasteh, senior immigration policy analyst at the institute, addressed the complaint by comparing first-time criminal conviction rates among undocumented immigrants in Texas and native-born Americans in Texas. He found that undocumented immigrants still committed crimes at a rate “32 percent below that of native-born Americans.”