Here is Robert Samuelson in the Washington Post on poverty statistics in the United States:

The government last week released its annual statistical report on poverty and household income. As usual, we -- meaning the public, the media and politicians -- missed a big part of the story. It is this: The stubborn persistence of poverty, at least as measured by the government, is increasingly a problem associated with immigration. As more poor Hispanics enter the country, poverty goes up. This is not complicated, but it is widely ignored.

The standard story is that poverty is stuck; superficially, the statistics support that. The poverty rate measures the share of Americans below the official poverty line, which in 2006 was $20,614 for a four-person household. Last year, the poverty rate was 12.3 percent, down slightly from 12.6 percent in 2005 but higher than the recent low, 11.3 percent in 2000. It was also higher than the 11.8 percent average for the 1970s. So the conventional wisdom seems amply corroborated.

It isn't. Look again at the numbers. In 2006, there were 36.5 million people in poverty. That's the figure that translates into the 12.3 percent poverty rate. In 1990, the population was smaller, and there were 33.6 million people in poverty, a rate of 13.5 percent. The increase from 1990 to 2006 was 2.9 million people (36.5 million minus 33.6 million). Hispanics accounted for all of the gain.

Consider: From 1990 to 2006, the number of poor Hispanics increased 3.2 million, from 6 million to 9.2 million. Meanwhile, the number of non-Hispanic whites in poverty fell from 16.6 million (poverty rate: 8.8 percent) in 1990 to 16 million (8.2 percent) in 2006. Among blacks, there was a decline from 9.8 million in 1990 (poverty rate: 31.9 percent) to 9 million (24.3 percent) in 2006. White and black poverty has risen somewhat since 2000 but is down over longer periods.

Only an act of willful denial can separate immigration and poverty.

Two comments:

• We need a better index to measure how poverty evolves with time, one which is unaffected by recent arrivals. Immigration may change in many ways: number of immigrants admitted per year, the financial situation of those immigrants, and so on. If we are interested in endemic poverty in the US, we need an index which is insensitive to all this.
  
• The tremendous decrease in poverty among blacks from 1990 to 2000 is another highlight of how so many things went so right for America during the Clinton era.