Interstate 99

This article is about the incomplete highway in Pennsylvania and New York. For the proposed highway in North Carolina, Virginia, Maryland, and Delaware, see List of future Interstate Highways § Interstate 99.

Interstate 99 marker
Interstate 99
Map
I-99 highlighted in red and Future I-99 in blue
Route information
Length98.34 mi[1] (158.26 km)
Existed1998 (1998)[2]–present
NHSEntire route
Southern segment
Length85.74 mi[1] (137.99 km)
South end
 I-70 / I-76 / Penna Turnpike / US 220 / US 220 Bus. near Bedford, PA
Major intersections
North end Future I-99 / US 220 / PA 26 in Bellefonte, PA
Northern segment
South end I-180 / US 15 / US 220 in Williamsport, PA
Major intersections
North end I-86 / NY 17 / NY 352 / NY 415 near Painted Post, NY
Location
CountryUnited States
StatesPennsylvania, New York
CountiesPA: Bedford, Blair, Centre
NY: Steuben
Highway system
← PA 98PA→ PA 99
← NY 98NY→ NY 99

Interstate 99 (I-99) is an Interstate Highway in the United States with two segments: one located in central Pennsylvania and the other in northern Pennsylvania into southern New York along US 15.[3] The southern terminus of the route is near exit 146 of the Pennsylvania Turnpike (I-70/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 an at-grade intersection with Musser Lane just before reaching I-80 near Bellefonte. 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. Within Pennsylvania, I-99 passes through Altoona and State College—the latter home to the Pennsylvania State University—and is entirely concurrent with US 220.

In November 2024, the northern segment was extended down US 15 to I-180 in Williamsport, entirely concurrent with US 15.[4] Long-term plans call for the two segments of I-99 to be connected using portions of I-80 and US 220 through Pennsylvania. The only current progress on the connection is the direct access interchange at I-80.

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 System Designation Act of 1995 by Bud Shuster, then-chair of the US House Committee on Transportation and Infrastructure, the bill's sponsor, and the representative of the district through which the highway runs. I-99 breaks the AASHTO numbering pattern associated with Interstate Highways, as it would be expected to lie east of I-97 but instead lies east of I-79 and west of I-81.

  1. ^ a b Starks, Edward (January 27, 2022). "Table 1: Main Routes of the Dwight D. Eisenhower National System of Interstate and Defense Highways". FHWA Route Log and Finder List. Federal Highway Administration. Retrieved January 21, 2023.
  2. ^ Cite error: The named reference aashto was invoked but never defined (see the help page).
  3. ^ [Staff writer] (June 28, 2014). "Corning Area Now Has 2 Interstates: US 15 Designated I-99 to Pa. Border". Star-Gazette. Archived from the original on July 15, 2014. Retrieved June 28, 2014.
  4. ^ Special Committee on U.S. Route Numbering (October 30, 2024). "2024 Annual Meeting Report to the Council on Highways and Streets" (Report). Washington, DC: American Association of State Highway and Transportation Officials. Retrieved November 12, 2024 – via AASHTO Route Numbering Archive.