Immigration Wave Delivers Economic Windfall. But There’s a Catch.

The influx of millions of unauthorized migrants in recent years has sparked a political firestorm that has paralyzed Congress and consumed election campaigns. But it also has a benefit: a bigger, faster-growing economy.

The precise scale of that economic boost was laid out in the Congressional Budget Office’s latest long-term budget and economic outlook, released Feb. 7. It estimates the labor force will be larger by 1.7 million potential workers in 2024 and 5.2 million more—about 3%—in 2033 than the nonpartisan agency expected one year ago. Gross domestic product—the value of all goods...