Manhattan's northern tip. In much of Midtown Manhattan, Broadway runs at a diagonal to the grid, creating major named intersections at Union Square (Park Avenue South/Fourth Avenue and 14th Street), Madison Square (Fifth Avenue and 23rd Street), Herald Square (Sixth Avenue and 34th Street), Times Square (Seventh Avenue and 42nd Street), and Columbus Circle (Eighth Avenue/Central Park West and 59th Street). "Crosstown traffic" refers primarily to vehicular traffic between Manhattan's East Side and West Side. The trip is notoriously frustrating for drivers because of heavy congestion on narrow local streets laid out by the Commissioners' Plan of 1811, absence of express roads other than the Trans-Manhattan Expressway at the far north end of Manhattan Island; and restricted to very limited crosstown automobile travel within Central Park. Proposals in the mid-1900s to build express roads through the city's densest neighborhoods, namely the Mid-Manhattan Expressway and Lower Manhattan Expressway, did not go forward. Unlike the rest of the United States, New York State prohibits right or left turns on red in cities with a population greater than one million, to reduce traffic collisions and increase pedestrian safety. In New York City, therefore, all turns at red lights are illegal unless a sign permitting such maneuvers is present, significantly shaping traffic patterns in Manhattan. Another consequence of the strict grid plan of most of Manhattan, and the grid's skew of approximately 28.9 degrees, is a phenomenon sometimes referred to as Manhattanhenge (by analogy with Stonehenge). On separate occasions in late May and early July, the sunset is aligned with the street grid lines, with the result that the sun is visible at or near the western horizon from street level. A similar phenomenon occurs with the sunrise in January and December. The FDR Drive and Harlem River Drive, both designed by controversial New York master planner Robert Moses, comprise a single, long limited-access parkway skirting the east side of Manhattan along the East River and Harlem River south of Dyckman Street. The Henry Hudson Parkway is the corresponding parkway on the West Side north of 57th Street. River crossings Being primarily an island, Manhattan is linked to New York City's outer boroughs by numerous bridges, of various sizes. Manhattan has fixed highway connections with New Jersey to its west by way of the George Washington Bridge, the Holland Tunnel, and the Lincoln Tunnel, and to three of the four other New York City