This book studies the transition from local to national timekeeping, a process that led to Standard Time the world-wide system of timekeeping by which we all live. Prior to the railroads adoption of Standard Railway Time in 1883, timekeeping was entirely a local matter, and America lacked any uniform system to coordinate times and public activities. For example, in the middle of the nineteenth century, Boston had three authoritative times, which differed by seconds and minutes. The story begins in the 1830s with the building of the first railroads. Since railway safety depended upon maintaining the temporal separation of trains through precise timing, railroads were the first to establish time standards to govern their operations. The railroads switch to five time standards indexed to the Greenwich meridian inaugurated the modern era of public timekeeping and led directly to cities adopting Greenwich-indexed civil time zones.