The poverty threshold in the US is defined by a standard developed and used since 1955, independent of geographical regions.. i.e. applied nationally rather than regionally or by rural, urban, or metropolitan area. The article Mismeasuring Poverty describes the big picture (here).
State policies in some cases attempt to adjust the national standard by applying factors to arrive at thresholds below which state aid is applied. This varies widely by state, however, and a function of political considerations rather than an objective accounting of poverty.
It occurred to me that as a society the standard(s) we use to define the poverty threshold is a measure of society's compassion... a compassion index of sorts. By that measure, among high income OECD nations we're near the least compassionate of all... 3rd worst of 19 such high income OECD's (2007/08 rankings.... possibly worse than that since then). See data here. This measure uses several measures of poverty.... not just income relative to median family income, but also including probability of not surviving beyond 40, adult illiteracy rate, & rate of long-term unemployment.
By the measure of poverty where income only is used (below 50% of median family), the US ranks even far worse... just ahead of Turkey and right behind Chile, Isreal, and Mexico in that order.
What is even more disconcerting however is the relationship of poverty rates to religiosity.... those states in the US with the greatest level of religiosity (source) are the ones with the greatest level of poverty.
Of the top 10 most religious states, 7 are in the top 10 with the highest levels of poverty (as % of families in poverty).
States with greatest percentage of families in poverty (US Census Bureau, 2009).. listed in order from greatest to least percentage. I listed the top 14... since all of the top 10 most religious states are within the top 14 most impoverished.
3 District of Columbia
5 West Virginia
6 New Mexico
11 South Carolina
14 North Carolina
Conversely, of the top 10 least religious states, 4 are within the top 10 with the least % of families in poverty.
Top 10 least impoverished states (Least percentage of families in poverty):
7 New Jersey
5 North Dakota
1 New Hampshire
Why this is interesting to me is because that those states that have the highest proportion of their populations professing that religion is important to them, appear to also be the least compassionate as measured by the proportion of families in the state that are at or below the national poverty level. Certainly this also reflects the states with the lowest per-capita incomes, hence likely to have a greater proportion of their population in poverty. But with such a high proportion in poverty, then the constituants of the state's politicians (federal and state level) would therefore be expected to have a higher level of say-so in electing politicians who would seek to minimize the plight of those in poverty ... i.e. increase aid to those in poverty.
On the other hand, perhaps the degree of religiosity is a function of the level of poverty (or poorness)... so that coping with ones poor economic plight increases one's dependance on religion just to cope with their condition. In the US however, I must wonder why poor people would use religion to cope when their voting for political representation should have greater beneficial consequence. Key words are "should have". For some reason that isn't immediately apparent this doesn't appear to be the case however. My best guess though is that it relates to who's interests the politicians actually represent... and those with the greatest wealth and income are also the ones that can finance their elections and re-elections.... thereby enforcing greater representation of those that have the most wealth and income even though that constituency is by far not in the majority.
Internationally, the nations with the least levels of poverty are also the ones least religious, and vice-versa: Sweden, Denmark, Hong Kong, Japan, Britain, & France are the least religious and have the least levels of poverty. In the international relationship, the US is the largest outlier. (source)
Maybe it has something to do with a society's greed index... those societies that put high value on greed (justified by the values of individualism) may also have the greatest levels of poverty.... but how religion plays into that might be related to how a society justifies high values on individualism.... using religion as the source of value of individualism.... although most religion's place higher value on caring for the poor than promoting individualism. In the US perhaps that norm has been hijacked by in some fashion conflating religion with individualism. A strange rationale if true.... one that defies rational logic.