Primary route
I-99
Central Pennsylvania toward the Southern Tier
Length100 mi
Designated1995
States2
Junctions1
About I-99
From Bedford, PA (I-70/I-76) to Painted Post, NY (I-86)
Interstate 99 is a north-south route in central Pennsylvania that extends north into the Southern Tier of New York, running roughly 100 miles through the Pennsylvania portion of the corridor. Its southern end is near Bedford, Pennsylvania, at the Pennsylvania Turnpike and US 220, and it runs north through Altoona and the State College area. The route continues toward the north-central part of the state and connects to the wider freeway network reaching the New York border region.
The highway passes through the ridges and valleys of central Pennsylvania, serving Altoona at the foot of the Allegheny Front and the university community of State College. The terrain is mountainous, with the route threading through valleys and across ridgelines in a part of the state that previously lacked a continuous freeway.
Interstate 99 is unusual for its route number, which does not follow the standard Interstate grid. Although a high number such as 99 would normally indicate a route near the East Coast, this highway lies west of Interstate 81 and east of Interstate 79, breaking the expected pattern.
State-by-state mileage
| State | Miles |
|---|---|
| Pennsylvania | 85.0 |
| New York | 15.0 |
| Total | 100 |
History
The Interstate 99 designation was unusual in that the number was written into federal law rather than assigned through the normal numbering process overseen by the American Association of State Highway and Transportation Officials. The designation was specified by Representative Bud Shuster of Pennsylvania, and the route was given its number in 1995.
The corridor was built and upgraded in stages over the following years to bring the central Pennsylvania route to Interstate standards.
Major cities and places
BedfordAltoonaState College
Did you know
- The route number was set by federal law rather than assigned through the usual numbering process.
- Its number breaks the standard Interstate grid, lying west of I-81 and east of I-79.
- The southern terminus is near Bedford, Pennsylvania, at the Pennsylvania Turnpike.
- It serves Altoona and the State College area in central Pennsylvania.