Interstate 26 in South Carolina

Interstate 26 (I-26) is an Interstate Highway in the U.S. state of South Carolina, running generally east–west for 221 miles (356 km) from near Landrum in Spartanburg County to U.S. Route 17 in Charleston. It is the longest Interstate Highway in South Carolina. I-26 traverses diverse landscapes, from the Blue Ridge Mountains to the Atlantic coastal plain, passing through the state's Midlands region and connecting major metropolitan areas including Spartanburg, Columbia, and Charleston.

The highway begins at the North Carolina state line and travels southeasterly, intersecting with major Interstates such as I-85 near Spartanburg, I-20 and I-77 in the Columbia metropolitan area, and I-95 near Holly Hill. Near its eastern terminus in Charleston, I-26 connects with I-526. Officially designated the James F. Byrnes Memorial Freeway, I-26 serves as a critical corridor for commerce and tourism in South Carolina.

Construction of I-26 began in 1957 in the Columbia area, with the first section opening in 1960. The entire 221 miles (356 km) route was completed by February 1969. Over the years, various sections of I-26 have been widened to accommodate increasing traffic, particularly around Columbia and Charleston. Ongoing and future projects aim to further improve capacity and safety along the corridor. I-26 has two auxiliary routes: I-126, a spur into downtown Columbia, and I-526, a beltway around Charleston.