San Francisco is the second most economically unequal metro area in the country, according to a study by the economist for real estate website Trulia, but the gap is widening faster here than anywhere else.

“Tensions over growing local inequality, therefore, are backed by the facts,” the study stated. “Nearly every major metro has seen the income gap between the rich and the poor grow since 1990, and the gap has widened faster in the last six years. The growth in inequality is more about the rich getting richer than the poor getting poorer, though both are happening. And where housing is less affordable, income inequality is more extreme.”

Fairfield County, Conn., tops the list of most unequal metros, followed by San Francisco, New York, Boston and Detroit.

The study looked at the household incomes of rich, median and poor people in the 100 largest metros from as early as 1990 to as late as 2012 using census data. San Francisco’s metro region included The City and Marin and San Mateo counties. “Rich” was defined as households in 90th percentile in terms of earnings. “Median” and “poor” were the 50th and 10th percentiles, respectively.

By looking at the divergence in income, Trulia ascertained the size of the income gap.

Such inequality has raised tensions between the affluent and everyone else, and locally the divide has even erupted into protests.

At least some of the rich and powerful have taken note.

At the urging of Mayor Ed Lee and others, Google and Salesforce.com have dipped into their profits for local handouts. But venture capitalists like Tom Perkins have fueled the flames of outrage by arguing that it’s the rich who are facing a class war.

Inequality was not the same in all regions across the U.S. The most unequal metros tend to be places were housing costs have spiked and growth is slower than in other regions.

There were outliers, however. Detroit was in the top five even though it has an inexpensive housing market. San Francisco, whose housing is among the country’s most expensive, has a robust economy.

Still, the major factor in inequality was housing costs. The report said those costs push out the poor as the more affluent bid for pricey homes.

The least unequal metro areas included several small cities in Florida. But cities like Salt Lake City and Raleigh, N.C., were notable in their relative income equality.Bay Area NewsIncome inequalitySan Francisco income inequalityTrulia

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