James Galbraith (via DeLong) in Mother Jones:
The rise of the Democrats brings some much-needed attention to the issue of income inequality, but while most observers focus on how income is distributed among people, it is also revealing to look at the distribution across places. This measure of income inequality, calculated using tax data recorded by county, actually declined quite sharply after 2000. Why? Because it tracks, with uncanny precision over more than 30 years, the nasdaq stock index. After declining in the early 1970s, both indices rose almost steadily until they reached an all-time peak in 2000; both fell thereafter.
In other words, income inequality in the United States has been driven by capital gains and stock options, mostly in the tech sector. This is what separates that mysterious top .01 of 1 percent from the rest of us: They’re the people who run Google, Oracle, and eBay.
County data confirm this: The big income winners in the late 1990s were concentrated in just four counties—Santa Clara, San Francisco, and San Mateo in California (all in the environs of Silicon Valley), and King County in Washington (Microsoft)—as well as in Manhattan, the home of the bankers who made it happen. Take the big tech counties out, and the rise in inequality between counties in the late 1990s disappears. And, of course, while these counties were big winners through 2000, they became the big losers in the Bush Bust.