“People are pouring across the southern border,” the Republican presidential candidate Donald Trump said in a debate in December. That image has helped to make immigration reform all but impossible in the current Congress, and it has reinforced the idea that we have lost control of migration into the United States.

In fact, the total number of undocumented migrants in the United States fell to 10.9 million in 2014, its lowest level since 2003. According to a report in January by the Center for Migration Studies, the size of the undocumented population has fallen each year since 2008; the number of Mexican-born undocumented migrants has dropped by more than 600,000 since 2010. Similarly, the Pew Research Center reported in November that “more Mexican immigrants have returned to Mexico from the U.S. than have migrated here since the end of the Great Recession.”

Tighter border security, along with the Obama administration’s surprisingly aggressive deportation policies, may be having a deterrent effect, but the C.M.S. researcher Randy Capps told The Atlantic, “The long-term trends in Mexico are driving a lot of this story.” That is, more jobs and a rising standard of living in Mexico are reducing the incentives to head north. So it is in the best interest of the United States to work with the Mexican government to improve economic conditions and reduce drug violence there—as opposed to building literal or figurative walls between the two nations. It is also time for a more civil discussion of legal status for the great majority of undocumented migrants who contribute to our economy and social life. The myth of people “pouring” across our borders in ever-increasing numbers should not go unchallenged in this election year.