What does a train number starting with 1xxx signify?

A train number starting with 1xxx indicates that the train originates or terminates at Jefferson Station or Suburban Station. This classification is significant because it helps passengers easily identify trains servicing major hubs within the transit system, particularly in the context of SEPTA's regional rail services. Jefferson Station and Suburban Station serve as major transfer points for passengers and are critical locations for the network, facilitating connections between different lines.

This numbering system allows for efficient organization and communication regarding train schedules and routes. Knowing that a train starts with "1" helps riders quickly understand that it is likely to be a local or regional service that connects key transit points within the city, streamlining their journey and planning.

The other choices refer to different lines or services that are identifiable by their unique numbering conventions and do not correspond to the significance of the "1xxx" starting sequence.