U.S. 12 follows all of Interstate 82 east from Yakima to Interstate 182 at Goose Gap. Interstate 182 dually carries U.S. 12 signage through Richland and Pasco, with U.S. 12 joining its original alignment from Lewis Street southeast to Burbank, Attalia Station and Wallula.
The surface route of U.S. 12 utilized Lewis Street west to 10th Avenue and the Green Bridge across the Columbia River. Turning westward through Downtown Kennewick, U.S. 12 used Columbia Drive to Columbia Park Trail and Kennedy Road west. When Interstate 182 was completed by 1986, U.S. 12 was relocated to share pavement with the freeway.
The Green Bridge, otherwise known as the Benton-Franklin Inter-County Bridge, opened on October 21, 1922 with private funding. The 23-foot wide span doubled as the Yellowstone Trail and was tolled until June 1931. U.S. 410 utilized the span until 1967 and U.S. 12 from 1967 until it closed on September 16, 1978, when the adjacent Cable Bridge was completed. The bridge sat unused for ten years until its demolition.