To evaluate this claim, we divide the population into two mutually exclusive groups—those who live in families headed by an individual who was born in the United States and those who live in families headed by an individual who was born abroad.
We use data from the Integrated Public Use Microdata Series (Census) rather than the Current Population Survey, because the CPS does not include information on country of birth prior to 1993.
Table 5 shows that between 1959 and 1999, the poverty rate among U.S. natives fell by almost 50 percent, from
20.6 percent to 12.4 percent, whereas poverty among the foreign born increased by 3 percentage points. The year 1959 is probably a poor starting point, however, since the poverty rate fell so much between 1959 and 1969, while a growing and
increasingly low-income immigrant population cannot explain much of the trend in poverty prior to 1980.
On the other hand, if we focus on the second half of the period, we see that while poverty rates among natives have changed little, poverty rates among immigrants have increased by nearly two percentage points, and the fraction of the population that is foreign born has increased by six percentage points. Taken together, these changes should put upward pressure on the poverty rate, but how much?