The National Academies of Sciences, Engineering, and Medicine appointed an
interdisciplinary task force to look at that question. It found that, on the contrary, “immigration has an overall positive impact on long-run economic growth in the United States.”
Immigration, the report says, has “little to no negative effects on overall wages and employment of native-born workers in the longer term.” Native-born teenagers who have not finished high school may work fewer hours, at least in the short term. (They won’t lose jobs.)
As far as the downside goes, that’s pretty much it.
On the upside, “the prospects for long-run economic growth in the United States would be considerably dimmed without the contributions of high-skilled immigrants” who create jobs for highly-paid and lower-income workers alike. And the study found that recent immigrants tend to have more education than earlier immigrants.
“Immigrants,” the report concludes, “are integral to the nation’s economic growth.”