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Interstate 99

Interstate 99 marker

Interstate 99
Route information
Length: 98.86 mi[1] (159.10 km)
Existed: November 6, 1998 (1998-11-06)[2] – present
Southern segment
Length: 85.780 mi[1] (138.050 km)
South end: I-70 / I-76 / PA Turnpike / US 220 near Bedford
North end: I-80 / US 220 near Bellefonte
Northern segment
Length: 13.08 mi[3] (21.05 km)
South end: US 15 at the Pennsylvania state line in Lindley
North end: I-86 / NY 17 / Southern Tier Expressway near Painted Post
Highway system
PA 98 PA PA 99
NY 98 NY NY 99

Interstate 99 (I-99) is an Interstate Highway with two segments: one located in central Pennsylvania, and the other in southern New York[4] in the United States. The southern terminus of the route is at exit 146 of the Pennsylvania Turnpike (I-70 and I-76) north of Bedford, where the road continues south as U.S. Route 220 (US 220). The northern terminus of the Pennsylvania segment is at I-80 near Bellefonte. The New York segment follows US 15 from the Pennsylvania–New York border to an interchange with I-86 in Corning. I-99 passes through Altoona and State College—the latter home to Pennsylvania State University—and is entirely concurrent to US 220, within Pennsylvania. Long-term plans call for I-99 to be extended southward along the US 220 corridor to an interchange with I-68 in Cumberland, Maryland.

Unlike most Interstate Highway numbers, which were assigned by the American Association of State Highway and Transportation Officials (AASHTO) to fit into a grid, I-99's number was written into Section 332 of the National Highway Designation Act of 1995 by Bud Shuster, then-chair of the U.S. House Committee on Transportation and Infrastructure, the bill's sponsor, and the representative of the district through which the highway runs. I-99 violates the AASHTO numbering convention associated with Interstate Highways, since it lies east of I-79 but west of I-81.


  • Route description 1
    • Pennsylvania 1.1
    • New York 1.2
  • History 2
    • Origins 2.1
    • Designation and Bald Eagle Ridge 2.2
  • Future 3
  • Exit list 4
  • See also 5
  • References 6
  • External links 7

Route description


  mi km
PA 85.78 138.05
NY 13.08 21.05
98.86 159.10

I-99 begins at an indirect interchange with US 220 and the Pennsylvania Turnpike (designated as I-70 and I-76) north of Bedford. 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. The interchange with the Turnpike requires drivers to use a short segment of US 220 Business to access the Turnpike at exit 146. North of the Turnpike junction, the limited-access highway becomes the Bud Shuster Highway as it heads through a rural portion of Bedford County. It connects to Pennsylvania Route 56 (PA 56) just west of the Bedford County Airport at exit 3 and PA 869 at exit 7 before crossing into Blair County. Here, it meets PA 164 north of East Freedom at exit 23 prior to entering the Altoona area.[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. This junction allows travelers to head west towards Ebensburg, Johnstown, and Pittsburgh. The freeway continues to Altoona itself, where it indirectly connects to PA 36 via exit 32. Unlike the original routing of US 220 which goes through the city center, I-99 and US 220 mostly bypass it to the east, connecting to the city via streets leading eastward from the downtown district. At the northern edge of Altoona, PA 764 joins the old alignment of US 220 and parallels I-99 north for 3 miles (5 km) toward Bellwood. PA 764 leaves old US 220 about 2 miles (3.2 km) south of Bellwood, however, and terminates at I-99 exit 39. Bellwood itself is served by exit 41, which leads to PA 865.[5]

Map of the Mount Nittany Interchange near State College

The highway veers northeastward from Bellwood to serve the borough of Tyrone, located at the junction of old US 220 and PA 453. Access to the borough is made by way of exit 48, which serves PA 453. Past Tyrone, I-99 and US 220 head through sparsely populated areas of Blair and Centre Counties. For this reason, only three exits exist between Tyrone and State College: exit 52, serving PA 350 and the small community of Bald Eagle, and exits 61 and 62, which connect to US 322 and the borough of Port Matilda. Here, US 322 joins I-99 and US 220 and follows them eastward to the State College area.[5]

I-99 north near Bald Eagle, Pennsylvania in October 2011

At exit 68 (US 322 Business), I-99 merges into the Mount Nittany Expressway, an older, northerly bypass of State College. I-99, US 220, and US 322 follow the expressway to the Mount Nittany Interchange, a directional T interchange located on the northern fringe of the Pennsylvania State University campus. 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. At this point, PA 26 joins the freeway and follows it to Bellefonte, served by exit 83 and PA 550. The southern segment of I-99 ends about 2.5 miles (4.0 km) later at an interchange with I-80, where PA 26 continues north and US 220 joins I-80 east.[5]

New York

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

The northern segment of I-99 is entirely concurrent with US 15, and starts at the Pennsylvania-New York border north of Lawrenceville, Pennsylvania. 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. The freeway enters a partial cloverleaf interchange with CR 5 (Smith Road). After CR 5, I-99 turns northeast through the town of Erwin, running to the west of the Indian Hills Golf Club. Making a gradual bend further to the northeast, the freeway crosses the Canisteo River and enters the hamlet of Erwins, where it enters a diamond interchange with NY 417 (Addison Road). After NY 417, it then turns alongside Norfolk Southern Railroad's Southern Tier Line (former Erie Railroad main line). Now paralleling the tracks and NY 417, I-99/US 15 crosses through Erwin, entering exit 11, which connects to NY 417 once again, next to Gang Mills Yard,[6] the site of the former Painted Post station.[7]

After Gang Mills Yard, I-99 crosses through the Gang Mills section of Erwin, entering a large interchange at the northern end of the neighborhood. Signed exit 12, this interchange serves CR 107 (Robert Dann Drive) via NY 417. After CR 107, I-99 enters a large interchange that utilizes several flyover ramps between I-99, US 15, I-86, and NY 17 (the Southern Tier Expressway). Ramps are also present, connecting to NY 352. This interchange serves as the northern terminus of both I-99 and US 15.[6]



2002 photo of the I-99 excavation, looking south from Julian at the area where acidic rock was exposed on Bald Eagle Mountain

Corridor O of the Appalachian Development Highway System was assigned in 1925, running from Cumberland, Maryland (Corridor E, now I-68) to Bellefonte (I-80) along US 220.[8] The portion in Pennsylvania, from Bedford north to Bald Eagle, was upgraded to a freeway in stages from the 1960s to the 1990s. The first section, from US 30 in Bedford to Pennsylvania Route 56 (PA 56) near Cessna, opened in the latter half of the 1960s.[9][10] Two more sections—from PA 56 north to modern exit 15 in Blair County and from Charlottsville (exit 45) to Bald Eagle—were completed in the 1970s.[10][11] The portion between exit 15 and Altoona (exit 33) was finished in the 1980s[11][12] while the segment between modern exits 33 and 45 was opened by 1997.[13]

In 1991, the Intermodal Surface Transportation Efficiency Act (ISTEA) was signed into law.[14] It included a number of High Priority Corridors, one of which—Corridor 9—ran along US 220 from Bedford to Williamsport, and then north on US 15 to Corning, New York.[15] The National Highway Designation Act of 1995 amended ISTEA; among these amendments were that "the portion of the route referred to in subsection (c)(9) [Corridor 9] is designated as Interstate Route I-99."[16] This was the first Interstate Highway number to be written into law rather than to be assigned by AASHTO. The number was specified by Representative Bud Shuster, who said that the standard spur numbering was not "catchy"; instead, I-99 was named after a street car, No. 99, that took people from Shuster's hometown of Glassport to McKeesport. I-99 violates the AASHTO numbering convention associated with Interstate Highways, since it lies east of I-79 but west of I-81.[17]

Designation and Bald Eagle Ridge

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.[2] In 2002, plans were set in motion to extend I-99 northeast from Bald Eagle to State College via Port Matilda.[18] The extension was fraught with issues, however. The proposed alignment for the highway north to Port Matilda proved to be controversial: while environmentalists called for I-99 to be constructed in the valley below Bald Eagle Ridge, the Pennsylvania Department of Transportation (PennDOT) and valley residents favored a routing that took the freeway above the valley and along the side of the ridge.[19] Farther north, the widening of Skytop, the mountain cut that US 322 uses to traverse Bald Eagle Ridge, resulted in the exposure of acidic pyrite rock in 2003.[18]

2006 photo of the westbound approach to the Mount Nittany Interchange. The blank spots on the overhead signs were reserved for I-99 shields.

Work on the segment ceased one year later[18] as PennDOT attempted to stop the flow of acidic runoff from the site. The state remedied the situation by removing 1,000,000 cubic yards (760,000 m3) of pyrite and replacing it with a mix of limestone and fill, a process that took two years and cost $83 million.[17] With the environmental issues settled, construction resumed on the portion of the freeway south of Skytop Mountain. The section from Bald Eagle to Port Matilda was opened to traffic on December 17, 2007,[20] while the remaining section between Port Matilda and the west end of the Mount Nittany Expressway near State College was completely opened on November 17, 2008.[18] In all, the Bald Eagle–State College section of I-99 cost $631 million to construct.[17]

I-99 was extended northeastward to meet I-80 northeast of Bellefonte following the completion of the Bald Eagle–State College segment. The connection was made by way of the pre-existing Mount Nittany Expressway and another, unnamed limited-access highway connecting the State College bypass to the Bellefonte area.[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. At the time, it was designated solely as PA 26.[10][11] It was widened to four lanes in 1997. The piece connecting the PA 26 freeway to the Mount Nittany Expressway was completed in 2002. US 220 was rerouted via US 322 and the new road, and the old alignment of US 220 north of US 322 was designated US 220 Alternate on May 30, 2003.[21]

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.[4]


"Future I-99 Corridor" sign on US 15 southbound north of Williamsport

Long-term plans for I-99 call for the freeway to be extended northeastward along US 220 from Bellefonte to Williamsport and northward along US 15 from Williamsport to I-86 in Corning, New York, as well as southbound along U.S. 220 to Cumberland, Maryland to intersect with Interstate 68.[22] Signs have been placed along the present US 220 and US 15 between Bellefonte and Corning—much of which are built to Interstate Highway standards—marking the route as the "Future I-99 Corridor". The entirety of US 15 north of Williamsport is a limited-access highway.

Some local Rochester, New York, area supporters have 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 metro area, be redesignated as I-99 once the I-80 to I-86 portion of that route is completed, positing that it is a logical extension of the I-99 corridor (I-99's predecessor, U.S. Route 15, originally extended to Rochester); no official moves to accomplish this have been forwarded, however.[23]

Exit list

State County Location mi[1][3] km Exit Destinations Notes
Pennsylvania Bedford Bedford Township 0.000 0.000 US 220 south to US 30 – Cumberland Continuation beyond I-70/I-76/Penna Tpk. South end of US 220 overlap
0.000 0.000 1 I-70 / I-76 / PA Turnpike – Pittsburgh, Harrisburg Indirect connection via US 220 Business
2.892 4.654 3 PA 56 (US 220 Bus. south) – Johnstown, Cessna
East St. Clair Township 6.597 10.617 7 PA 869 – St. Clairsville, Osterburg Low clearance at exit
King Township 10.112 16.274 10 Blue Knob State Park
Blair Greenfield Township 14.900 23.979 15 Claysburg, King (US 220 Bus. north)
Freedom Township 22.798 36.690 23 PA 36 / PA 164 to US 22 east – Roaring Spring, Portage, Hollidaysburg
Allegheny Township 28.045 45.134 28 US 22 – Ebensburg, Hollidaysburg
Logan Township 30.507 49.096 31 Plank Road (US 220 Bus.)
31.803 51.182 32 To PA 36 (Frankstown Road)
32.921 52.981 33 17th Street
Antis Township 38.521 61.994 39 PA 764 south – Pinecroft
41.193 66.294 41 PA 865 north – Bellwood
45.004 72.427 45 Tipton, Grazierville, DelGrosso's Amusement Park
Tyrone 47.529 76.491 48 PA 453 – Tyrone
Snyder Township 51.592 83.029 52 PA 350 (US 220 Bus. south) – Bald Eagle, Philipsburg
Centre Worth Township 61.437 98.873 61 Port Matilda (US 220 Alt. north)
62.243 100.170 62 US 322 west – Philipsburg South end of US 322 overlap; southbound exit and northbound entrance; northbound exit is via exit 61
Patton Township 68.993 111.033 68 Gray's Woods, Waddle
69.706 112.181 69 US 322 Bus. east (Atherton Street) Northbound exit and southbound entrance
70.200 112.976 69 Valley Vista Drive – Park Forest Southbound exit and northbound entrance
71.122 114.460 71 Toftrees, Woodycrest
College Township 73.944 119.001 73 US 322 east – State College, Lewistown North end of US 322 overlap
75.067 120.809 74 Innovation Park, Penn State University Northbound exit is part of exit 73
Benner Township 76.484 123.089 76 Shiloh Road
78.991 127.124 78 PA 150 – Bellefonte Signed as 78A (south) and 78B (north)
Spring Township 81.232 130.730 80 Harrison Road Northbound exit and southbound entrance
81.728 131.528 81 PA 26 south to PA 64 – Pleasant Gap South end of PA 26 overlap
83.605 134.549 83 PA 550 – Bellefonte, Zion
North end of freeway
85.780 138.050 I-80 / US 220 north (US 220 Alt. south) – Williamsport, Dubois
PA 26 north – Howard
North end of US 220 and PA 26 overlap
Gap in route
New York Steuben Lindley 0.00 0.00 US 15 south Pennsylvania state line; begin/end concurrency with US 15
6.36 10.24 6 CR 5 – Presho
Erwin 8.16 13.13 8 NY 417 – Erwin, Addison
11.12 17.90 11 NY 417 – Gang Mills
11.69 18.81 12 Robert Dann Drive (CR 107) Southbound exit and northbound entrance
12.10 19.47 12 I-86 west / NY 17 west / Southern Tier Expressway west – Jamestown, Rochester Exit 44 (I-86 / NY 17); northbound exit and southbound entrance
12.68 20.41 13A I-86 east / NY 17 east / Southern Tier Expressway west – Binghamton, Corning Exit 44 (I-86 / NY 17); northbound exit and southbound entrance; begin/end concurrency with US 15
13.08 21.05 13B NY 352 – Riverside, Downtown Corning Northbound exit and southbound entrance
1.000 mi = 1.609 km; 1.000 km = 0.621 mi

See also


  1. ^ a b c
    • Bedford County (PDF)
    • Blair County (PDF)
    • Centre County (PDF)
  2. ^ a b
  3. ^ a b
  4. ^ a b
  5. ^ a b c d
  6. ^ a b
  7. ^
  8. ^
  9. ^
  10. ^ a b c
  11. ^ a b c
  12. ^
  13. ^
  14. ^
  15. ^
  16. ^
  17. ^ a b c d
  18. ^ a b c d
  19. ^
  20. ^
  21. ^
  22. ^
  23. ^

External links

  • Interstate 99 at New York Routes
  • Interstate 99 at Pennsylvania Highways
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