the arteries of Center City, and originate from a loop around Philadelphia City Hall. The naming system of the streets differs by neighborhood, although the main north-south streets are numbered in South Philadelphia, West Philadelphia, and Lower North Philadelphia similar to how they are numbered in Center City. One example of a naming system is in South Philadelphia, where east-west streets use the surnames of former governors of Pennsylvania, starting with Reed Street and ending with Pattison Avenue. Several east-west streets in North Philadelphia are named after counties in Pennsylvania. Many other streets are named after locally or nationally significant people. During the 20th century, several streets were renamed to honor individuals, such as John F. Kennedy Boulevard. Addresses The system for assigning street addresses was enacted in 1858. In areas with a consistent grid, the street address numbers increase by intervals of 100s for each block, starting with Front Street for east-west streets and Market Street for north-south streets. For example, 1200 South Street would refer to the intersection of 12th & South Street, and 500 North 17th Street is 5 blocks north of Market Street. Expressways The main expressways of Philadelphia are the Delaware Expressway (I-95), which travels along the Delaware River, and the Schuylkill Expressway (I-76), paralleling the Schuylkill River for most of its route. Other expressways are the Vine Street Expressway (I-676), running between the Schuylkill Expressway and Delaware Expressway through downtown Philadelphia, the Roosevelt Expressway (US 1), a freeway portion of the Roosevelt Boulevard, and Woodhaven Road, an expressway connecting to I-95 to the south.. Bridges Delaware River Philadelphia is connected to New Jersey across the Delaware River by four bridges, three of which are maintained by the Delaware River Port Authority. The oldest is the Benjamin Franklin Bridge, which opened in 1926, and was the world's longest suspension bridge span until the opening of the Ambassador Bridge in 1929. The Benjamin Franklin Bridge connects Camden, New Jersey with Center City, thus making it a main crossing between Philadelphia and New Jersey. The Benjamin Franklin Bridge carries seven lanes of roadway, two rail lines of the PATCO Speedline, and two pedestrian walkways. The longest bridge between Philadelphia and New Jersey is the Walt Whitman Bridge, which connects South Philadelphia to Gloucester City, New Jersey. The Walt Whitman Bridge opened in 1957, with a total length of and main span length of . The bridge carries