At its 27 ground hubs, an automated sorting system relies on information picked up by cameras and laser scanners as packages whiz by at 540 feet per second.

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Increased communication via phone and cloud computing is another contributory factor, but the main reason for the decline is that mail sorting is becoming automated, with robots replacing people.

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Yet the chief reason for the decline, Shatkin says, is that mail sorting has become mostly automated, and robots are replacing people.

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