A few years ago, I found myself on the platform of a train station in Tanzania. There under the ubiquitous photograph of the country's then president were two fading portraits of two statesmen from an earlier time, Chairman Mao Zedong and Julius Nyerere, first president of independent Tanzania. These two political giants were the main architects of the Tanzania-Zambia Railway (TAZARA), which was completed in 1976. The Chinese-built railway allowed Zambia to circumvent apartheid South Africa and white minority ruled Rhodesia and export its copper out of the Tanzanian port of Dar es Salaam. The 1,860-kilometer-long railway remains an enduring...