Interstate 684

Northward, I-684 begins as two separate spur routes. The primary spur, which is officially designated I-684, begins at the White Plains–Harrison line at exit 9A of the Cross-Westchester Expressway (I-287) in Westchester County, New York. The other, officially designated as New York State Route 984J (NY 984J) but signed as I-684 in the northbound direction, begins in Harrison north of exit 16A (formerly exit 26) on the Hutchinson River Parkway. NY 984J has one independent exit with Manhattanville Road, which serves Manhattanville College, before joining the spur to I-287. The spurs, I-287 and the Hutch, surround an office park. From the junction of the two spurs, the Interstate Highway takes a straight course to the north-northwest through a wooded corridor with Century Country Club on the west and residences on the east. After the Barnes Lane overpass a mile and a half (2.4 km) north of the spurs, it veers to the north-northeast for a half-mile (800 m) before turning to the north alongside Rye Lake, part of Kensico Reservoir, one of many that provide water to New York City. It remains in an increasingly narrow strip of woods between the lake and Westchester County Airport into its first exit, Airport Road, 4.4 miles (7.1 km) from its southern terminus. NY 120 parallels the highway to the east.

Signs at Connecticut state line

Just north of that exit, NY 120 crosses over the road. Immediately after this exit, I-684 crosses the Connecticut state line. Signage indicates this, but it retains its New York reference markers as it curves more to the northeast for the next 1.41 miles (2.27 km) through wooded and swampy country in the western corner of Greenwich. There is no exit in Connecticut. A mile (1.6 km) after it reenters New York, in the town of North Castle, it reaches its next exit, where NY 22 serves that community and the nearby hamlet of Armonk. The short section of I-684 in Connecticut is owned by the Connecticut Department of Transportation (CTDOT), but maintenance and repairs to the stretch are performed by the New York State Department of Transportation (NYSDOT), with the cost of maintenance being reimbursed to New York by Connecticut.

Past that exit, it bends even more to the northeast, continuing past houses, parks, and golf courses located amidst dense woodlands. At Byram Lake Reservoir, it returns to a northward heading for a mile (1.6 km), crossing into the town of Bedford. The highway then curves northeasterly and then to the northwest once the reservoir is past. The Arthur W. Butler Memorial Sanctuary, a private nature preserve, replaces it on the east of the highway. Just south of the exit for NY 172, I-684 bends northwest again.

Over the next two miles (3.2 km), the Interstate curves gently back and forth, maintaining its generally northerly heading, as its median strip widens slightly. The surrounding lands start to include some more cleared lots, larger estates that were once small farms. At the northern end of this section, a rest area serves southbound traffic. The highway passes Bedford Hills Correctional Facility for Women, one of New York's two main women's prisons, a short distance to its west, and then bends northwest into the most extensive junction since its beginning: the northern terminus of the Saw Mill River Parkway.

Diagram of Interchanges 5 and 6

The Saw Mill merges from the southeast, its two roadways forming service roads flanking I-684 for the next mile (1.6 km) as it passes a southern extension of Muscoot Reservoir just east of the hamlet of Katonah. Entry from the Interstate to the parkway (and NY 117, which has its northern terminus at the parkway just below the Interstate) is from the southbound lanes only. A half-mile (800 m) north of the merger, the frontage roads merge into the Interstate at the exit for NY 35, serving Katonah and the hamlet of Cross River to the east. After that exit, the electrified tracks of Metro-North Railroad's Harlem Line parallel the highway to the west. They cross into the town of Lewisboro. A mile (1.6 km) north of that point, NY 22 parallels on the east. A northbound-only exit leads onto it, allowing access to NY 138, which crosses the Interstate at the hamlet of Goldens Bridge. Its train station is prominently visible on the west side of the highway.

North of that station is the North Salem town line. NY 22 detours slightly eastward, away from the interstate, for a mile (1.6 km). When it returns, the roads and the railroad tracks bend strongly to the northeast, following the Croton River on their west. After a mile (1.6 km), this brings them to I-684's next exit, at NY 116, again for only northbound traffic but with southbound entry. Purdy's station is also adjacent to the highway but is screened from view by a line of trees. A quarter-mile (400 m) to the north, NY 22 crosses under to the opposite side. A short distance later, the Harlem Line veers northwest, followed quickly by NY 22, as the Interstate veers northeast. The Hardscrabble Road exit serves both directions and, via NY 22, allows access to the nearby hamlet of Croton Falls. One mile (1.6 km) past that junction, I-684 crosses into Putnam County and the town of Brewster.

Within a thousand feet (300 m) of the county line, the Brewster rest area serves northbound traffic. Beyond, the highway turns slightly more to the east, then swings back to the north into its northern terminus at I-84. An almost-complete cloverleaf interchange guides traffic east to Danbury, Connecticut, or west toward Newburgh. Traffic continuing north remains on a limited-access route, designated but not signed as NY 981B, to the last signed exit with the concurrent routes of US Route 6 (US 6) and US 202 adjacent to East Branch Reservoir. The highway carrying both roads parallels I-84 at this point. Just past it, I-684 officially ends as NY 22 merges onto the highway, having left the US 6/US 202 concurrency. Over the next quarter-mile (400 m), the two roadways slowly converge into a two-lane surface road by the at-grade intersection with Sodom and Old Milltown roads, continuing north toward Pawling.[3]

I-684's exit numbers are sequential. While NYSDOT is transitioning to mileage-based numbers, there are no announced plans to convert I-684 exit numbers.

State	County	Location	mi [4][5][6]	km	Exit	Destinations	Notes
New York	Westchester	White Plains–Harrison line	0.00	0.00	—	I-287 – Rye, White Plains	Southern terminus; exit 9A on I-287
			0.15	0.24	—	Westchester Avenue
		Harrison	1.23	1.98	1	Hutchinson River Parkway south – New York City	Exit 16A on HRP; southbound exit/northbound entrance only; access via NY 984J
		North Castle	4.18	6.73	2	NY 120 – Westchester County Airport	Also serves SUNY Purchase
Connecticut	Fairfield	No major junctions
New York	Westchester	North Castle	7.63	12.28	3	NY 22 – Bedford, Armonk	Signed as Exits 3N (north) and 3S (south) northbound
		Town of Bedford	12.72	20.47	4	NY 172 – Bedford, Mount Kisco
			14.86	23.91	Bedford Rest Area (southbound)
			16.94	27.26	5	Saw Mill River Parkway south to NY 117 – New York City	Southbound exit and northbound entrance; northern terminus of Saw Mill Parkway
			17.55	28.24	6	NY 35 – Cross River, Katonah	Also serves Katonah station
		Lewisboro	20.01	32.20	6A	NY 22 to NY 138 – Goldens Bridge	Northbound exit to NY 22 and southbound entrance from NY 138; other movements via exit 8; also serves Goldens Bridge station
		North Salem	22.48	36.18	7	NY 116 – Purdys, Somers	Northbound exit and southbound entrance; other movements via exit 8; also serves Purdy's station
			23.93	38.51	8	Hardscrabble Road – Croton Falls	Also serves Croton Falls station
	Putnam	Brewster	25.30	40.72	Brewster Rest Area (northbound)
			28.21	45.40	9	I-84 – Newburgh, Danbury	Signed as Exits 9E (east) and 9W (west); Exit 68 on I-84
			28.47	45.82	10	US 6 / US 202 / NY 22 south – Brewster
		Southeast	28.53	45.91	—	NY 22 north – Pawling	Northern terminus
1.000 mi = 1.609 km; 1.000 km = 0.621 mi       Incomplete access

The entire route is in Harrison, Westchester County.

mi [4][7]	km	Exit	Destinations	Notes
0.00	0.00		Hutchinson River Parkway south – New York City	Southern terminus; Exit 16A on northbound HRP
0.40	0.64	—	Manhattanville Road
1.53	2.46		I-684 north – Brewster	Northern terminus; Exit 1 on southbound I-684
1.000 mi = 1.609 km; 1.000 km = 0.621 mi