Market Street, originally known as High Street, is a major east–west highway and street in Philadelphia, Pennsylvania, United States. The street is signed as Pennsylvania Route 3 between 38th Street and 15th Street. A short portion of the road continues west from Cobbs Creek Parkway to Delaware County, adjacent to Philadelphia. The street also serves as the dividing line for the "north" and "south" sides of the city. All north-south addresses in the city start at zero at Market Street.