Interstate 380 (abbreviated I-380) is a spur highway in northeast Pennsylvania that connects Interstate 80 with Interstate 81 and Interstate 84. The northern terminus of I-380 is at Interstate 81 at the Throop-Dunmore Interchange in Dunmore; the southern terminus is in Tunkhannock Township at the junction with Interstate 80. The entire length of the highway is 28.10 miles (45.22 km).
Interstate 380 begins at Interstate 80 in Tunkhannock Township. The highway passes Gouldsboro State Park and Tobyhanna Military Reservation just past Exit 8. At Exit 24, I-380 merges with Interstate 84 and later ends at the interchange with Interstate 81.
I-380 is a north-south route with exits numbers beginning in the south according to Interstate Highway System guidelines. The northern section of I-380 that is multiplexed with I-84 uses I-84 exit numbers that begin in Scranton.
Prior to receiving its current designation, I-380 had several other designations. When the initial numbers for the Interstate System were assigned in 1957, the Scranton–New York route (including the current I-380) was designated Interstate 82. This changed the next year, and the Scranton-Stroudsburg connection became Interstate 81S, a spur of I-81.
In 1961, construction began on a short section of the route between what is now Exit 2 for PA 435 (then part of U.S. Route 611) and its northern terminus at I-81 outside of Scranton. This section was opened in 1962 as part of US 611. In 1964, the designation of the proposed road was changed again to Interstate 81E and construction began on the section between the southern terminus at Interstate 80 and Exit 3 for PA 940 near Pocono Manor. This section was built at the same time as the connecting section of I-80 and both opened in 1965.
In 1967, construction on the road was restarted on a 17-mile (27 km) southern section from PA 940 to PA 423 and PA 507 to the Dorantown Road overpass, and, in 1968, was expanded to the sections from PA 423 to PA 507 and the Dorantown Road overpass to PA 307. This section opened in 1970 with US 611 multiplexed onto the portion between Exit 8 (now PA 611) and Exit 13 (PA 507) adjacent to Gouldsboro State Park.
Interstate 380 received its current name 1973, the same year the northern section was upgraded to Interstate standards. In 1974 and 1975, work commenced on the final sections from PA 307 to the Shutters Road underpass and Shutters Road to PA 435, respectively. This included an interchange with Interstate 84 was opened to traffic in 1976 as an east-west highway with mileage-based exit numbers. These mileage-based numbers were scrapped by 1977 and replaced with eight sequential numbers beginning in Scranton. Mileage-based exit numbers were revived in 2001 when the Pennsylvania Department of Transportation renumbered its Interstate System exit numbers. I-380 was redesignated as a north–south highway so that its exit numbers would commence from I-80 in the south.