SALEM, Va. -

UPDATE 5:48 p.m.: The tractor-trailer accident has been cleared on I-81 South at mile marker 138 in Salem.

Traffic is moving.

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A tractor-trailer accident is causing traffic backups on I-81 South in Salem. 

The accident happened at mile-marker 138.

The right lane is closed.

According to VDOT, traffic is backed up for approximately three miles.

Drivers should watch for slowing traffic.