At the start of McKendry's crisp chronicle of the construction of Boston's-and the country's-first underground public transit system, the author puts the project in historical context. By the 1890s, the city's growing population, fueled by that century's various waves of immigration, and its burgeoning industrial scene had created enormous congestion on its trolley- and carriage-choked streets. The Boston Transit Commission proposed constructing ""an interconnected system of subway and elevated railway lines,"" a project McKendry succinctly describes as ""a new and dangerous job requiring a mastery of both terrain and technology."" He then offers a detailed account of how engineers and workers met the physical and technological challenges, specifying the construction methods, labor forces and equipment involved in each phase of this vast endeavor, and panel illustrations offer step-by-step subterranean views of the progress. Reproductions of pertinent newspaper articles, some entertaining trivia and human-interest notes effectively balance the narrative's necessarily technical tone, which some readers may find rather dry. Those familiar with Boston will appreciate McKendry's copious references to the city's landmarks, neighborhoods and streets, which he charmingly depicts in meticulous, sepia-toned illustrations, many based on construction photos and architectural drawings. Convincingly mimicking vintage photographs with remarkable clarity, the art brings this intriguing undertaking-and turn-of-the-last century Boston-very much to life. Ages 8-up.