One reason is that the traditional cities usually have assets that benefit the edge cities, too.

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Some are traditional urban cores such as New York and some are suburban edge cities that offer jobs along with affordable houses and short commutes.

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Buying farmland on the edge of big cities would have been an even better play.

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But it's how a place like Houston squanders part of its cost edge over other cities.

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Having the ability to do business and spend time with friends and loved ones is a competitive edge that Dubai offers more than other cities in the Middle East.

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But pressures of family, demands for dowry and domestic harassment - and violence - push many such young, married women over the edge in the country's teeming cities and towns.

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Outside of these cities, the handset will be limited to 2G EDGE speeds only.

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One area Apple's own software still has an edge is its integration of Flyover which offers interactive photo-realistic views of selected cities using 3D-rendered graphics within its maps app.

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Dubbed EDGE (for Enhanced Data for Global Evolution), it is available in more than 7, 500 cities, but offers slower download speeds of around 100 to 130 kilobits per second.

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