The question of poverty in Texas is in some ways linked to, but is distinct from, the question of inequality in Texas. The first deals with who is poor - how many people in Texas live below the official poverty line, what counties are poor, how poverty is distributed racially and geographically, and the like. But investigating this question tells us nothing about the difference between the wealthy and the poor in Texas, which is exactly what inequality asks about. Numerous ways have been developed to measure inequality; probably the best known of these is the Gini Index or Coefficient.
The Gini Index compares the actual distribution of a population and income with a hypothetically perfect distribution. For example, if a society had a perfectly equitable distribution of income, everyone would receive exactly the same income; there would be no need to talk about the wealthiest third or quarter or fifth of the population. However, in every human society of any size and duration, someone always has more income than someone else, so the question is not one of whether inequality exists (it does), but rather one of how much inequality there is.
The Gini Coefficient ranges from 0.0 to 1.0; the greater the income inequity in a society, the higher the Gini Coefficient. If a society existed where every member had exactly the same income as every other member, its Gini Coefficient would be 0.0. On the other extreme, if in a society one member received all of the income and no one else received anything, then its Gini Coefficient would be 1.0.
What societies have the least and greatest degrees of inequality? As a rule, the Scandinavian countries (Norway, Sweden, Denmark, Finland) have the world's lowest Gini coefficients (around .20-.25); some countries in Africa and Latin America have the highest (.60 or higher). The United States as a nation has a Gini Coefficient of around .47; this figure has been rising steadily since the 1980s.
The Gini Coefficient has been calculated for Texas. In 1999 it was .47, while in the same year it was .46 for the United States as a whole. In 1979, twenty years earlier, both the US and Texas had coefficients of .415, meaning that inequality had risen both nationally and in Texas. In 1999, Texas was tied with Florida for the sixth highest Gini Coefficient of all of the states; only New York (.499), Louisiana (.483), Mississippi (.478), Connecticut (.477) and California (.475) had higher. In 2007, Texas had the 4th highest (.473), with only Louisiana (.478), Mississippi (.48) and New York (.5) registering higher Gini Coefficients. Texas is only one of three states to rank in the top five in each category - that is, to be in the top five in poverty rate and income inequality (the other two are Mississippi and Louisiana).
We have already noted that Texas has some of the poorest counties and places in the United States. But it also has some of the wealthiest. In 2006, for example, Plano (a Dallas suburb) had the highest median household income of any city over 250,000 in the United States - $71,560. Sugarland (a Houston suburb) had the ninth highest median income - $86,231 - in the country for cities between 66,000 and 250,000. And Frisco, a city in the same size category as Sugarland, had the second lowest poverty rate in the United States at 2.1%.
These figures all argue that Texas is among the most unequal of states in the United States; its wealthy are wealthy on a nation-wide basis, while its poor live, by some standards, in the poorest places and counties in the entire country.