In 2016, the birth rate of new born in the United States fell to a record low, and the academics argued that this trend would hurt economic growth; as more baby boomers enter retirement age, tax revenues need to be moved to the increasingly large groups of older people, which means this requires more taxpayers and that the lower birth rate is not conducive to future tax revenue growth. Nevertheless, the total population of the United States is still growing. Anbound believes that one of the key factors is the increase in immigration. From this perspective, although the outside world is concerned that Trump will further increase restrictions on foreign immigrants, the reality is that fertility rate falls to historically low levels will make it difficult for the United States to maintain long-term restrictions on immigration policy.