We still don't know what started the chain reaction on Thursday. Whatever the initial cause, however, the current guess is that a local event turned into an epic blackout because the transmission network has been neglected. That is, the power industry hasn't spent enough on the control systems and safeguards that are supposed to prevent such things.
And the cause of that neglect is faith-based deregulation.In the past, electric power was considered a natural monopoly. It was and is impractical to have companies competing either to wire up homes and businesses, or to build long-distance transmission lines. Because effective competition was impossible, power companies were given local monopolies, and regulated to keep them from exploiting customers.
These regulated monopolies took responsibility for the whole system — transmission and distribution as well as generation. Then came the deregulation movement. It argued that a competitive market could be created in power generation (though not in transmission and distribution), and in much of the country utilities were forced to sell off their power plants.
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http://www.nytimes.com/2003/08/19/opinion/19KRUG.html