Interstate 99

The northern segment is entirely concurrent with US 15, beginning at I-180 in Williamsport northward into New York to an interchange with I-86 in Corning.

It begins concurrent with US 220, which continues south from the interchange toward the Maryland state line as a two-lane highway known as the Appalachian Thruway.

North of the turnpike junction, the freeway becomes the Bud Shuster Highway as it heads through a rural portion of Bedford County.

[5] In Hollidaysburg, a borough south of the city, I-99 and US 220 connect to US 22 at exit 28, a large modified trumpet interchange.

At the northern edge of Altoona, PA 764 joins the old alignment of US 220 and parallels I-99 north for three miles (4.8 km) toward Bellwood.

Beaver Stadium, the home of the Penn State Nittany Lions football team, is visible from I-99 at this point.

US 322 continues east through the interchange to follow the Mount Nittany Expressway while I-99 and US 220 split from US 322 and head northeastward toward Pleasant Gap, which I-99 connects to via exit 81 and PA 26.

A four-lane freeway through the Steuben County town of Lindley, I-99 crosses through a rock cut, making a large bend to the north and bypassing the hamlet of Presho.

After CR 5, I-99 turns northeast through the town of Erwin, running to the west of the Indian Hills Golf Club.

After CR 107, I-99 enters a large interchange that utilizes several flyover ramps between I-99, US 15, I-86, and NY 17 (Southern Tier Expressway).

[17] On November 6, 1998, AASHTO formally approved the I-99 designation, which initially extended 51.2 miles (82.4 km) from the Pennsylvania Turnpike in Bedford to PA 350 in Bald Eagle.

[1] In 2002, plans were set in motion to extend I-99 northeast from Bald Eagle to State College via Port Matilda.

[18] Work on the segment ceased one year later[18] as PennDOT attempted to stop the flow of acidic runoff from the site.

[17] The portion of the latter highway north of the PA 26 interchange was originally built in the 1970s as a two-lane freeway connecting Pleasant Gap to I-80.

[citation needed] The piece connecting the PA 26 freeway to the Mount Nittany Expressway was completed in 2002.

On June 27, 2014, New York Governor Andrew Cuomo announced that the interstate-grade US 15 freeway from the Pennsylvania border to I-86 in Corning was officially signed as I-99.

The new interchange will eliminate local access between PA 26 (Jacksonville Road) and I-80, which will be provided by a new exit two miles (3.2 km) to the east.

[23][24] The local access interchange between PA 26 and I-80 was funded in part by a $35-million federal grant, with a total estimated cost of $52 million.

The second phase, the Jacksonville Road (PA 26) project is expected to take two years, cost $6.9 million and completion is now scheduled for the middle of 2026.

[26] During a 2002 taskforce meeting for I-99, it was suggested that I-390, which extends north from I-86 24 miles (39 km) west of the I-86/I-99 junction near Corning and which crosses I-90 and terminates in the greater Rochester metropolitan area, be redesignated as I-99 once the I-80 to I-86 portion of that route is completed.

I-99 north near Bald Eagle, Pennsylvania in October 2011
I-99/US 220 northbound at split with US 322 eastbound in College Township , near State College
Looking southward along US 15 (now I-99) from the Smith Road overpass in Presho prior to the road's completion. The highway previously narrowed from four to two lanes in the background
I-99/US 15 entering New York
2002 photo of the I-99 excavation, looking south from Julian at the area where acidic rock was exposed on Bald Eagle Mountain
I-99 and US 220 northbound past PA 865 near Bellwood
2006 photo of the westbound approach to the Mount Nittany Interchange on westbound US 322. The blank spots on the overhead signs were reserved for I-99 shields, which have since been put up.
"Future I-99 Corridor" sign on US 15 southbound north of Williamsport