It begins at the Pennsylvania state line in Mina and follows the Southern Tier Expressway east through Corning to Binghamton and the Quickway from Binghamton east to Woodbury, where it turns south to follow the Orange Turnpike to the New Jersey state line near Suffern, where it connects to New Jersey Route 17.

Eventually, the entire east–west portion of NY 17 from the Pennsylvania border to Woodbury will become I-86 as projects to upgrade the route to Interstate Highway standards are completed.

It serves 11 counties (Chautauqua, Cattaraugus, Allegany, Steuben, Chemung, Tioga, Broome, Delaware, Sullivan, Orange, and Rockland), passes through the cities of Salamanca, Olean, Corning, Elmira, and Binghamton, and enters the vicinity of several others, including Jamestown and Middletown.

The portion of NY 17 in the vicinity of Waverly is actually located in Pennsylvania; however, it is maintained by the New York State Department of Transportation (NYSDOT).

Past NY 280, the freeway runs adjacent to the northern extent of the Allegany State Park and follows the reservoir and the connecting Allegheny River eastward to Salamanca.

Between the two rivers, which intersect in Pennsylvania, the general corridor runs just north of the state line in New York.

The highway and railroad head east along Oquaga Creek to Deposit (exit 84), where they turn southeast along the West Branch Delaware River, where NY 17 briefly becomes an arterial road.

The route parallels the Thruway as it proceeds through a disjointed piece of Harriman State Park and enters the town of Tuxedo.

[8] South of Arden Valley Road, NY 17 briefly exits Harriman State Park and enters the hamlet of Southfields, where it intersects with County Route 19 (CR 19) and passes by the Red Apple Rest, a former restaurant and roadside attraction.

On the other side of the county line, NY 17 enters the village of Sloatsburg, where it meets Seven Lakes Drive and connects to CR 72 by way of a modified trumpet interchange.

Here, NY 17 turns to the southwest, merging onto the Thruway southbound at exit 15A, traversing a sparsely developed area of the village of Hillburn.

The road ran from the Pennsylvania state line at Great Bend through Binghamton, Owego, and Elmira to Bath.

[12][13] Route 4 exited the city on US 11 and followed it to Kirkwood Center, a hamlet adjacent to the eastern junction of NY 17 and I-81.

From this point to Harriman, except for one section near Middletown, the path Route 4 followed became the basis for the Quickway several decades later.

Between Kirkwood Center and Hancock, Route 4 utilized what was later upgraded into the Quickway (via Broome CR 28 from Windsor to Deposit).

[12][13] The portion of the Liberty Highway between Suffern and Harriman became part of legislative Route 39-b in 1911;[13][14] however, this designation was removed on March 1, 1921.

[15] Another auto trail, the West Shore Route, also followed this section of the Liberty Highway, but proceeded north from Harimman along modern-day NY 32.

[25] The explosive growth of the tourism industry in the Catskill Mountains region, which began in the 1930s and intensified after World War II, stretched the rural road to its limits.

Scores of hotels, resorts and bungalow colonies attracted hundreds of thousands of vacationing New Yorkers, whose cars left the two-lane NY 17 hopelessly jammed in summer.

It would replace intersections with well-spaced access ramps, separate grades with flyovers, and allow safe travel at up to 65 miles per hour (105 km/h).

[27] The first segment of the new highway extended from Fair Oaks to Goshen, bypassing the city of Middletown to the northeast.

The highway was first proposed by New York Governor Thomas Dewey in 1953,[30] and the first sections of the Southern Tier Expressway were completed in the mid-1960s.

At the time, NY 17 followed the entirety of two of the four open sections (Steamburg to Salamanca and Owego to the Broome County line) and part of a third (Corning to Lowman via Elmira).

The large portion of the road west of Chautauqua Lake was widened to four lanes as part of a project completed in 1997.

[38] On December 3, 1999, the westernmost 177 miles (284.85 km) of NY 17 were replaced by I-86,[39] a new route that had been written into law a year earlier.

[39] In September 2013, the Federal Highway Administration (FHWA) approved a 15.8-mile (25.4 km) extension of the I-86 designation from exit 56 in Elmira to the Tioga county line.

This was a part of Governor Andrew Cuomo's goal to convert the entirety of the New York Thruway to cashless tolling.

On March 18, 2019, Howe died from injuries sustained when a tractor-trailer collided with his DOT truck as he and others were performing highway safety work on NY 17.

As part of the project, a four-ramp parclo was built, which replaced the prior exit 125, located 4,000 feet (1.2 km) west.

[53][54][55] New York State Department of Transportation wants to begin a $1.3 billion project in the Catskill Mountains section of the route.