The early railroads needed to have printed schedules so that people would know when the trains were running. Up to that point, time was told locally. Of course, there were multiple accidents including a major one in August 1853 when two trains collided on the same track killing 14 people because their engineers didn't coordinate their watches. This led to a General Time Convention of Railway companies which in turn led to multiple petitions for Congress to have time zones throughout the US. They were not interested. So, the railroads went ahead and owned their own time zones. So, when Vanderbilt built Grand Central he established Eastern Standard Time and embedded a large clock off of the main waiting room.