(WBIR) -  Engineers have reopened Interstate 40 at the Tennessee and North Carolina line. NCDOT originally said the closure would last until around midnight, but crews wrapped up work and opened the interstate at 6:00 p.m.

Twenty miles of I-40 were closed from Exit 451 in Tennessee to Exit 20 in North Carolina to allow NCDOT crews to clear dangerous rocks from some of the cliffs above the interstate. Thousands of drivers were detoured along I-81 and I-26.

Rockslides are a longtime danger that constantly hangs over the heads of 23,000 vehicles that drive through that portion of I-40 on a daily basis. The beauty of the Appalachians have a long history of crashing down along a 30-mile stretch known as "the gorge" where the interstate hugs the steep cliffs along the Pigeon River.

NCDOT spokesperson Jordan Ashley Baker said Thursday's closure started a week ago when North Carolina crews noticed some sizable rocks along the shoulder near the Harmon Den exit at mile marker 7. Engineers monitored the mountainside and ultimately decided to close the interstate and clear the dangerous rocks on their own terms.

Although the entirety of Thursday's work was done in the westbound lanes next to the hillside, engineers have good reason to close the interstate in both direction.