Interstate 87 (New York)

Interstate 87 (I-87) is a 333.49-mile-long (536.70 km) north–south Interstate Highway located entirely within the US state of New York. I-87 is the main highway that connects New York City and Montreal. The highway begins at exit 47 off I-278 in the New York City borough of the Bronx, just north of the Robert F. Kennedy Bridge. From there, the route runs northward through the Hudson Valley, the Capital District, and the easternmost part of the North Country to the Canada–United States border in the town of Champlain. At its north end, I-87 continues into Quebec as Autoroute 15 (A-15). I-87 connects with several regionally important roads: I-95 in New York City, New York State Route 17 (NY 17; future I-86) near Harriman, I-84 near Newburgh, and I-90 in Albany. The highway is not contiguous with I-87 in North Carolina.

I-87 was assigned in 1957 as part of the establishment of the Interstate Highway System. The portion of I-87 south of Albany follows two controlled-access highways that predate the Interstate Highway designation, the Major Deegan Expressway (locally known as "the Deegan") in New York City and the tolled New York State Thruway from the New York City line to Albany. North of Albany, I-87 follows the Adirondack Northway, a highway built in stages between 1957 and 1967 (finished just in time to bring Americans to the World Exhibition held in Montreal that year). Early proposals for I-87 called for the route to take a more easterly course through the Hudson Valley and extreme southwestern Connecticut between New York City and Newburgh. These plans were scrapped in 1970 when I-87 was realigned onto the Thruway between Westchester County and Newburgh.

I-87 makes up most of the major strategic corridor between New York City, the largest metropolitan area in the US, and Montreal, the second-largest metropolitan area in Canada (formerly the largest). The New York State Department of Transportation (NYSDOT) considers the route important for commerce, as it connects with numerous highways in the region and serves approximately 80 million people in the Mid-Atlantic states, New England, and Quebec. Motorists can connect to multiple highways to travel farther south along I-95 through the Mid-Atlantic states or farther east into New England.

I-87 and the Major Deegan Expressway begins in the Bronx at the northern approach to the Robert F. Kennedy Bridge, where it connects to the Bruckner Expressway (I-278) at a directional T interchange. The route heads west from the interchange, paralleling loosely with the Harlem River through Mott Haven. After one mile (1.6 km), the highway makes a turn to the north, mirroring a change in the nearby river's course. It passes by Yankee Stadium on its way to Highbridge, where the Deegan connects to the Cross Bronx Expressway (I-95 and US Route 1 [US 1]) at the eastern approach to the Alexander Hamilton Bridge. The Deegan remains in close proximity to the Harlem River until the waterway turns westward at Kingsbridge to form the northern edge of Manhattan. The Major Deegan Expressway is named after Major William Francis Deegan.

North of Kingsbridge, the expressway follows a generally northeasterly alignment, passing through the center of Van Cortlandt Park as it connects to Mosholu Parkway and Jerome Avenue. Mosholu Parkway also links the Deegan to the Henry Hudson and Saw Mill River parkways, which run parallel to the Major Deegan Expressway through the western Bronx and Manhattan. Past Jerome Avenue, the freeway gains a pair of service roads and heads north to the New York City line, where it becomes the New York State Thruway as it passes into Westchester County. The last northbound exit on the Deegan connects to McLean Avenue, located north of the city line in Yonkers. The exit 14 ramp leads to the service road in the Bronx but does not meet McLean Avenue until it crosses the county line. Southbound access to McLean Avenue is provided by Thruway exit 1 in Yonkers.

At the New York City–Yonkers border, I-87's mainline continues onto the New York State Thruway and northward through Yonkers and southern Westchester County. The first few exits serve various local streets, with exit 1 serving Hall Place, exit 2 providing access to Yonkers Raceway & Empire City Casino and exit 3 serving the Cross County Shopping Center. At exit 4, I-87 connects to the Cross County Parkway, an east–west parkway providing access to the Saw Mill River, Bronx River, and Hutchinson River parkways. The north–south parkways and I-95 run parallel to the Thruway through Southern Westchester. The Bronx River parkway leaves to the northeast midway through Yonkers, while the Saw Mill and Sprain Brook parkways follow the Thruway out of the city.

All three highways take generally parallel tracks to Elmsford, where I-87 directly intersects the Saw Mill River Parkway at exit 7A. Not far to the north is exit 8, a semi-directional T interchange with I-287 (the Cross Westchester Expressway). I-287 joins the Thruway here, following I-87 west across the Hudson River into Rockland County on the Tappan Zee Bridge. I-87 and I-287 remain overlapped for 15 miles (24 km) through the densely populated southern portion of Rockland County, meeting the Palisades Interstate Parkway and the Garden State Parkway Connector, with the latter providing access to the Garden State Parkway in New Jersey. The Thruway continues generally westward to Suffern, where I-87 and I-287 split at a large semi-directional T interchange (exit 15) only about a half mile (0.80 km) from the New Jersey border. At this point, I-287 heads south into New Jersey while I-87 and the Thruway turn northward into the valley of the Ramapo River.

The Thruway continues north as a six-lane tollway through the river valley toward Harriman, where it encounters the Woodbury toll gantry, the southeastern end of the main line's major closed toll system. The barrier is located on the mainline within exit 16 (NY 17), a trumpet interchange. Along with the mainline barrier in Harriman, a toll gantry exists on the exit 16 ramp midway between the Thruway and NY 17 exit 131 (NY 32). Now a completely tolled highway, the Thruway heads northward as it narrows to four lanes, roughly paralleling the Hudson River to the river's west as it serves the city of Newburgh, village of New Paltz, and city of Kingston, indirectly connecting to the short I-587 in the latter.