There are six standard time zones throughout the United States, with a seventh encompassing Puerto Rico and the Virgin Islands. However, before these were established, it was nearly impossible to accurately schedule trains because every town kept its own time! Before 1883, almost every town decided their own times based on sunrise and sunset, which was extremely inaccurate.
For example, if you were at one town and it was noon, you could go to a town only a couple of miles away and it could be 3! When railroads became the chief mode of transportation, the government encountered a huge problem coordinating what time the trains were supposed to arrive. In response, they developed standardized time zones in the Standard Time Act of 1918, allowing transportation and communication to happen much more easily!