Final answer:
In the sentence about SEPTA in Philadelphia, "train" means a series of connected rail vehicles that transport people around the city and to suburban areas.
Step-by-step explanation:
The student has asked about the meaning of the word "train" as used in a sentence describing SEPTA in Philadelphia. In this context, "train" refers to a series of rail vehicles that are connected and move along a railroad track to transport people from place to place within a city or to its suburbs. SEPTA, or the Southeastern Pennsylvania Transportation Authority, operates such trains in Philly for this purpose. The passage provided talks about the suburbanization of America, where commuter trains played a vital role.
Trains are an essential part of urban development and can greatly influence the economics and social makeup of cities. They are also a critical component of public transportation, enabling citizens to commute between different areas of a city, like the way downtown Philadelphia connects to its suburbs. Key components like transport infrastructure are examined by geographers when considering how government investments like miles of highways, streets, and electrical lines benefit industry and residential areas.