Mollie Orshansky, an economist and statistician who devised an equation in the mid-sixties to measure poverty while working for the Social Security Administration.

Dave Schechter
CNN Senior National Editor

It may be difficult to define "middle class," but the federal government can tell you exactly what it takes to be poor in America.

In 2009, that would be household income of $22,050 for a family of two adults and two children and $10,830 for a single adult under age 65.

Using that formula, 12.7 percent of the American population – more than 38 million people – lives in poverty.

As more jobs are lost and more homes are lost to foreclosure more people may be sliding toward that less-than-magical barrier.

Nonetheless, these figures are dubious, if not meaningless.

Why?

Well, the formula that determines the poverty line was created in 1963-64 using data from 1955.

1955?

Ike was President.

Rev. Martin Luther King was leading a bus boycott in Montgomery, Alabama.

Disneyland opened in Anaheim, California.

The Brooklyn Dodgers – yes, Brooklyn – beat the Yankees in the World Series.

The formula basically is based on what percentage of household income a family of four in 1955 would spend for food, on a diet "designed for temporary or emergency use when funds are low," multiplied by three to account for one-third of household income.

The Consumer Price Index is used to adjust the line upward annually.

How did we get here?

Mollie Orshansky.

Mollie, an expert in economics and statistics, was working for the Social Security Administration as a Social Science Research Analyst when she used Agriculture Department data from 1955 to devise an equation to measure poverty, later adopted by the Johnson administration for its "war on poverty."

The line then was set at $2,442 for that family of four.

A separate formula gave the rural poor less than the urban poor, but that index eventually went away.

What's changed?

Needless to say, "that" America no longer exists.

In 1955, Americans spent about one-third of their household income on food.

Today's it's one-seventh.

We spend a greater percentage of our money on health care – a lot more.

We spend more for energy – gas prices, heating and cooling our homes.

We spend more on housing.

We spend on child care (a concept that barely existed in 1955, when it was assumed most mothers stayed at home).

The existing "one size fits (almost) all" formula doesn't account for a lot of things, such as differences in the cost-of-living between various regions or between big cities vs. small towns.

Critics maintain that by failing to include various forms of public assistance payments received by low-income people, the extent of poverty is over-stated.

If the value of food stamps and other programs were counted as income at the current poverty level, many people no longer would be classified as poor.

So why not change the formula?

Like anything else involving government, once it gets rooted, it's hard to remove.

If you change the formula and move the line up, the number and percentage of people nationally classified as poor will go up.

"Nobody wants to see that happen on their watch," says Deborah Johnson, editor at the Institute for Research on Poverty, based at the University of Wisconsin.

Some cities, counties, states and congressional districts could see increases in their percentage of poor that would vault them ahead of others in this undesirable category.

By most estimates the federal government has spent at least several trillion dollars combating poverty over the past four-plus decades and where there's federal money there are politicians who don't want to see their pork sliced or pulled.

Who is pushing for change?

Members of Congress have introduced bills.

Think tanks have issued reports.

The National Academy of Sciences, which brings together the smartest of the smart, has recommended fixing the formula's flaws.

Advocates for the poor have lobbied for a more generous bottom line.

New York Mayor Michael Bloomberg went so far as to order his city to come up with its own formula, so that the city could better target assistance. The National Center for Children in Poverty estimated that in New York City the figure for a family of four would be close to $50,000; more than twice the current national guideline