The economists find that, between 1990 and 2016, 16 percent of all US inventors were immigrants. More than that, they find that the "average immigrant is substantially more productive than the average US-born inventor." Immigrant inventors produced almost a quarter of all patents during this period. These patents were disproportionately likely to be cited (a sign that they were valuable to their fields) and seem to have more financial value than the typical native-born patent. The economists also find evidence suggesting that immigrant inventors help native-born inventors become more productive. All in all, the economists estimate that immigrants are responsible for roughly 36% of innovation in America.

As for why immigrant inventors tend to be so productive and innovative, the economists entertain various explanations. Immigrant innovators may be motivated to come — and are able to come — to the United States because there's something special about their character, intelligence, or motivation. Or maybe it's because they live, work, and think differently when they come here. The economists find these immigrants tend to move to the most productive areas of the country. They tend to have a greater number of collaborators when they work here. And, as the economists write, they also "appear to facilitate the importation of foreign knowledge into the United States, with immigrant inventors relying more heavily on foreign technologies and collaborating more with foreign inventors."