State Route 240 (SR 240) is a state highway in the U.S. state of Washington. It travels diagonally from northwest to southwest within Benton County, serving the Hanford Nuclear Reservation and the Tri-Cities region. The highway begins at a junction with SR 24 and travels around Richland on a limited-access bypass. From there, it briefly overlaps Interstate 182 (I-182) and continues southeast as a freeway along the Columbia River into Kennewick, terminating at an interchange with U.S. Route 395 (US 395). SR 240 is one of the busiest highways in the Tri-Cities region, with a daily average of 76,000 vehicles on a section crossing the Yakima River Delta. The riverfront route between Richland and Kennewick was part of a 19th-century wagon road and the Inland Empire Highway, a state road established in 1913. It was incorporated into US 410 in 1926 and was part of US 12 from 1967 to 1986. The highway through the Hanford Nuclear Reservation was established as a state highway in the 1950s and opened on July 14, 1965, to connect Richland to the Vernita Bridge on SR 24. Route description SR 240 begins at an intersection with SR 24 west of the Hanford Nuclear Reservation in northwestern Benton County. SR 24 continues west towards Yakima and north across the Hanford Reach of the Columbia River on the Vernita Bridge. SR 240 travels southeasterly along Cold Creek Valley at the foot of the Yakima Ridge and Rattlesnake Hills, forming the boundary between the Saddle Mountain National Wildlife Refuge (part of the Hanford Reach National Monument) and the rest of the Hanford Site, including the Laser Interferometer Gravitational-wave Observatory. Cold Creek empties into the Yakima River near the Horn Rapids Dam, where the highway intersects SR 225, which continues southwest to Benton City. About downstream from the dam, SR 240 enters the city of Richland and continues its southeasterly course along the north side of the Yakima River. The highway passes the city's landfill and a suburban golf course before reaching an intersection with Stevens Drive and Jadwin Avenue at the edge of Richland's residential neighborhoods. From the intersection, SR 240 turns southwest onto the six-lane Bypass Highway, which acts as a divided highway with limited intersections that travels around the west side of Richland. Jadwin Avenue continues southeast from the intersection as a business route of SR 240, while Stevens Drive continues north to the Pacific