Who makes America great? Immigrants do!!! Immigrants from Mexico, El Salvador, and African nations such as Nigeria are all performing better than the US-born, shows a new study. "The typical explanation offered for this kind of immigrant achievement is some inherent quality resulting from cultural differences, such as a strong work ethic or placing a value on education. But the working paper offers a more tangible explanation for the mobility gap: Immigrants tend to settle where there is more economic opportunity and take jobs that are below their true skill level." This is true for a lot of immigrants I know, including myself.