Interstate 180 spurs north from I-80 and PA 147 near the borough of Milton to Williamsport and the Lycoming Valley. The rural freeway mirrors the course of the Susquehanna River West Branch north from McEwensville to Muncy. Turning west ahead of Lycoming Mall, I-180 travels around the borough of Montoursville by Williamsport Regional Airport (IPT) to Downtown Williamsport.
U.S. 220 overlaps with Interstate 180 from Montoursville west to Williamsport and the Susquehanna Beltway. U.S. 15 accompanies I-180 between the Market Street Bridge to South Williamsport and the west end at Lycoming Creek. U.S. 220 west to Lock Haven and I-80, and U.S. 15 north to the New York state line, are both a part of the future Interstate 99 corridor.
Interstate 180 was established by AASHTO on October 1, 1983 after the final segment of the PA 147 freeway between I-80 and Williamsport opened to traffic in 1982. Work on the initial segment of PA 147 started in 1969.1