Interstate 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 southern New York. 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 New York segment follows US 15 from the Pennsylvania–New York border 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. Long-term plans call for the two segments of I-99 to be connected using portions of I-80, US 220, and US 15 through Pennsylvania.

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 violates the AASHTO numbering convention associated with interstate highways, as it should lie to the east of I-97 but instead lies east of I-79 and west of I-81.