Positive Selection Puzzle

In class, we discussed the positive selection "puzzle" on immigration. Today, many of the immigrants coming into the U.S. are of higher skill. In my opinion, this could be due to the fact that immigrants, upon arrival, typically earn less than natives and eventually catch up over time. Transportation costs (i.e. train, plane, car, and some other indirect costs) may have increased from the initial decrease in the 19th century, making it difficult for lower skilled workers to come especially if these costs need to be paid upfront. The fact that high skill immigrants are coming into the U.S. will allow these new workers to compete in the job market. Because immigrants can be hired at a lower wage than natives, high skill immigrants in the U.S. can pose a threat to high skill natives in the job market because of the fact that firms can hire high skill immigrants at a lower wage than their native counterpart. This phenomenon of positive selection does remain a puzzle but can be explained in many different ways. Perhaps low skilled workers in other countries receive a higher minimum wage than here in the U.S. which is why we don't see any negative selection. There is also the possibility that the U.S. offers one of the highest returns to an education when compared to other countries. Overall this issue does require additional extensive research and an answer revealed.