In the 19th century, one of the largest municipal challenges facing American cities was horse manure. In New York alone, over 100,000 horses produced an estimated 2.5 million pounds of manure daily. Cities deployed vast public resources to manage this avalanche of waste. It was the defining logistical crisis of the age — until the automobile arrived, and with it, an entirely new paradigm of urban transport. Now imagine if, on the eve of that shift, civic leaders had focused all their efforts ...