Daniel Engber explores the evolution of the progress bar in The New York Times:

Is a progress bar a tool to make us more efficient or a sop that helps us pass the time? Its ancestor, the pen-and-paper “progress chart,” showed up in the early 20th century and was hailed at the time as a major innovation. It “refers all facts to the irreducible and final element of human life — time,” wrote Walter Polakov, an early pioneer in project management (and dedicated Marxist), in 1923. “Because it is true to the human dimension, it is both human and humane; hence it obliterates conflicts between men and management, promotes the fullest exercise of man’s creative forces and places work in its proper relation to life.”