In his 8/31/16 speech on immigration, Donald Trump suggested there is a direct, causal link between “illegal immigration” and violent crime, social security and Medicare abuse, unemployment and low wages, and outright “chaos and lawlessness”. As appealing as that might seem for those in need of a convenient scapegoat, the evidence is arrayed against it.

Start with Mr. Trump’s counterfactual: “Countless Americans who have died in recent years would be alive today if not for the open border policies of this administration.” His causal factor—the alleged open border policy—is problematic given the facts. The number of border agents has quintupled in the last eighteen years and, as a result, apprehensions at the border have plummeted to a mere fraction of what they were in 2000. Lower employment opportunities in a weaker U.S. economy have undoubtedly diminished the pull for migrants. But more stringent immigration enforcement has also been a factor. Deportations, the do-all and end-all of Mr. Trump’s proposal, are at an all-time high under President Obama, so much so that he is under fire from liberals for his deportation record.

The loss of lives to violent crime is a tragedy, and crimes are committed by individuals that are present in our communities. From the fact that some are immigrants we cannot infer that all immigrants are criminals. In fact, while it is notoriously difficult to obtain credible data, studies repeatedly show that immigrants have significantly lower crime rates than the native-born. Since immigrants who commit crimes are likely to be deported they have a greater incentive to be prudent: they have more to lose from breaking the law. Interestingly, second-generation migrants have crime rates that approximate those of the general population, which suggests that their criminal involvement rises with assimilation, an avowed goal of Mr. Trump’s policy.

People who emigrate tend to be motivated and ambitious, searching for better lives. Do they find them by reducing “jobs and wages for American workers”? The impact of low-skilled migration—legal or not—on wages is much more highly contested than Mr. Trumpâs assertions would suggest. At the very least, no simple causal relation exists between immigration and wages. Much depends on whether migrants and local workers substitute or complement each other, the impact that new arrivals have on older migrants, and the context of the local economy. By most estimates the impact of migration on local wages is likely to be modest, with some studies even suggesting it might be positive.

Lost in Mr. Trump’s portrayal of immigrants is the fact that they are a boon to the receiving communities. A recent article in the Economist cites a study showing that a 2007 crackdown on illegal migrants in Arizona actually shrank its economy by 2%. Immigrants can, and in many cases do create jobs, help drive innovation, and make the locals more prosperous. They do not “draw much more out from the system than they will ever pay in”. “Illegal workers”, as Mr. Trump calls them, are generally ineligible for most federal public benefits programs, including the vilified Affordable Care Act. In point of fact, undocumented workers pay into the system by using false social security numbers, which means they will never collect the benefits—the opposite of what Mr. Trump asserts. Even lawful permanent residents must wait at least five years before they are eligible for benefits, and when they are eligible, studies show that they use benefits at lower rates and with a lower average value of benefits per recipient than the native-born.

Illegal migration is a symptom of a dysfunctional immigration regime which clearly requires comprehensive reform. But attributing our social and economic woes to it where the facts do not warrant it is disingenuous and, in the present context, demagogic.