Prior to the 19th century, time was a local matter. Each town set a public clock to noon when the sun was at its highest point. Towns close together could be on different times. This system worked well enough, until the railroads arrived. Travelers found schedules confusing, since each stop followed a different local time. It was often hard to know exactly when a train would arrive or depart. The problem was solved in 1883, when the United States adopted the four time zones we know today.