No Super Zips in Memphis (Only Germantown in Shelby County)

A Washington Post analysis of the latest census data shows that more than a third of Zip codes in the D.C. metro area rank in the top 5 percent nationally for income and education. But what makes the region truly unusual is that so many of the high-end Zip codes are contiguous. They form a vast land mass that bounds across 717 square miles. It stretches 60 miles from its northern tip in Woodstock, Md., to the southern end in Fairfax Station, and runs 30 miles wide from Haymarket in Prince William County to the heart of the District up to Rock Creek Parkway.

One in four households in the region are in a Super Zip, according to the Post analysis. Since the 2000 Census on which Murray based his analysis, Washington’s Super Zips have grown to encompass 100,000 more residents. Only the New York City area has more Super Zips, but they are a much smaller share of the total of that region’s Zip codes and are more scattered.

Zip codes are large swaths of territory, and people from many different walks of life live in them. But many Washington neighborhoods are becoming more economically homogenous as longtime homeowners move out and increasing housing prices prevent the less affluent from moving in. The eventual result, in many cases, is a Super Zip. And because the contiguous Super Zips are surrounded by areas that are almost as well-off, it’s possible to live in a Super Zip and rarely encounter others without college degrees or professional jobs.

“It’s a megalopolis of eggheads,” said William H. Frey, a demographer with the Brookings Institution. Frey said Washington is an example of how the country is compartmentalizing itself into clusters of people with different backgrounds and world views.

“It’s a magnet for people who grew up elsewhere and came here because they want to be in a place that has an atmosphere of intellectual curiosity. But it means we’re somewhat isolated. A lot of people here may study and advocate for what’s going on in the rest of the country, but they can’t feel what’s going on if it doesn’t touch them.”

The growing number of people living in Super Zips here is redefining and reshaping the region, turning modest inner-suburb neighborhoods into upscale enclaves and outer-suburb farmland into sprawling housing developments, often gated.

Yet many who live in these rapidly evolving communities do not think of themselves as rich or elite. The cost of living, particularly for housing, eats up a large chunk of the two incomes it typically takes to afford a comfortable home in a good school district.

Life surrounded by affluence can also breed worries that might seem absurd to people who do not live in Super Zips — such as whether to hire a professional tennis coach to help a child make the school team, or get an iPhone for a child in elementary school. Some question whether their children can achieve the same level of comfort as adults they know now.

So do the children themselves.

“My parents set me up with something great,” said Heather Burns, 23, adding that she grew up hearing her Loudoun home town of Ashburn described as “Cashburn” — as in “cash to burn.”

Burns said being raised in an area with good schools gave her a foundation to succeed. Even so, she said she may soon move away: “I can’t afford to keep up their lifestyle.”