The United States covered a large part of land from East to West. Traditionally, even town had their own time, determined by a sundial at noon.
However, this became problematic as noon in one city could be very difficult from a noon in another city. As the railroads expanded it was deemed impossible to run the operations with every town, station and city having a separate time.
It was also dangerous as different times could result in collisions.
Eventually, the Railroads came up with an idea to divide Mainland United State into four different time zones so that it was easier to manage.
This eventually helped to develop the official time zones in the country.
