Legal immigration flow has increased in the past four decades, and has remained at roughly 1 million people obtaining lawful permanent resident status every year since 2001. The unauthorized immigrant population increased from about 4 million in 1990 to about 12 million in 2007. But researchers estimate net zero illegal immigration flow from 2007 to 2014, due to the number of unauthorized immigrants leaving the country after the economic recession. Preliminary research from 2015 suggests net illegal immigration may have increased.
Rather than “decades of record immigration,” out of the top ten highest levels of all time, five occurred since 1990 and five before 1915.But measuring immigration in terms of the absolute number of permanent residents is narrow and misleading. The biggest problem is that it implies that a million immigrants entering China, with a population of 1.4 billion, would have the same effect on employment as a million entering Estonia with a population of 1.2 million. Clearly, to understand the impact of immigration, you need to control for the size of the destination country.
Unemployment is highest when immigration is lowest. During years when immigration was above the historical average, unemployment was 5.7 percent. During all other years, it was 7.2 percent, a difference of 1.5 percent. If you exclude years where unemployment dropped solely because of the draft, during the World Wars, the difference rises to 1.8 percent. . . .When unemployment is high in the top H-1B fields, employers submit dramatically fewer applications. Companies hire foreign workers when they are making general increases in employment, not when they are laying off workers.To be clear, immigrants are not causing the unemployment rate to move up or down. The economic literature on this point is quite unambiguous: immigrants cause essentially no effect on the unemployment rate one way or another. Rather, the causation is the other direction. Immigrants come during periods of economic growth when companies are hiring new workers, both immigrants and natives.