K-18 from US-81 to the western boundary of Lincoln County has been designated "Medal of Honor Recipient Donald K. Ross Memorial Highway".

As K-18 enters Ottawa County, it takes a due east bearing, traveling through Tescott and meeting US-81 north of Salina.

K-18 crosses the Kansas River at the Riley County line and travels through Ogden into Manhattan.

In a November 23, 1955 resolution, a 0.246 miles (0.396 km) spur route of K-18 was built on the western side of Manhattan.

[4] Then in a November 14, 1956 resolution, the new alignment of K-18 was to be built from the western end of the spur westward.

[11][12] The section of K-18 from I-70 in Grandview Plaza to K-113 in Manhattan has been rebuilt into a limited-access divided freeway, a project that began in 2012.