The highway narrows to two lanes and continues southeast along the Central Washington Railroad, a branch of the BNSF Railway,[3][4] changing course to bypass the city of Moxee on its south side.

[9] SR 23 turns northeast and follows the south wall of the Wahluke Slope before traveling due east across the Saddle Mountain National Wildlife Refuge and into Adams County.

[8] The highway leaves the Hanford Reach National Monument and forms the boundary between Adams and Franklin counties for several miles, briefly turning to cross a section of the Saddle Mountains.

[23][30] In response, Representative Donald H. Magnuson introduced a Congressional bill to reimburse $581,721 to the state (equivalent to $4.83 million in 2023 dollars),[31] but it was vetoed by President Dwight D. Eisenhower in September 1957.

[32][33] From January 1954 to December 1955, Army Corps of Engineers constructed a dirt road on the north side of the Columbia River between Vernita and White Bluffs, passing through a less-restricted portion of the Hanford Site.

The road was built as part of an agreement between the state and federal governments that was negotiated during the lawsuit, as an alternative to re-opening SSH 11A across the Hanford restricted zone.

[29] As part of the agreement with the federal Atomic Energy Commission, the highway was ringed by fences and signs prohibiting parking and loitering, as well as controlled traffic signals that would allow for a large-scale evacuation of the Hanford area.

[49][50] Congestion on a two-mile (3.2 km) section of SR 24 between I-82 and the east side of the Yakima River had worsened by the late 1990s and prompted the state government to consider a $35 million replacement and expansion project.

[51] The project was combined with a floodplain restoration plan proposed by the county government in response to a major flood in 1996 and originally considered building a second bridge upriver and realigning the highway.

[52] A revised plan placing the higher replacement bridge next to the existing crossing, saving costs and environmental mitigation for 7 acres (2.8 ha) of wetlands, was adopted in 2002 and funded by the legislature's 2003 Nickel Program gas tax.

[55][56] In 2008, the state government also built a series of passing lanes along SR 24 between Silver Dollar and Cold Creek in response to increased truck traffic.