The Chicago–Kansas City Expressway is a highway that runs between Chicago, Illinois, and Claycomo, Missouri. The road is known as Route 110 in Missouri and Illinois Route 110 (IL 110) in Illinois. IL 110 was created through legislation on May 27, 2010, as the designated route for the Illinois portion of the Chicago–Kansas City Expressway.

The Expressway starts in downtown Claycomo, Missouri on Interstate 35 and leaves the city in a northeast direction. In Cameron, Missouri, the route turns east on U.S. 36 and crosses the state including driving through Chillicothe, Missouri and Macon, Missouri. East of Hannibal, Missouri, the route continues east on I-72 through Hannibal and across the Mississippi River.^[3] U.S. 36 and Interstate 35 in Missouri are now in the process to have the comprehensive sign package similar to Illinois along the Chicago–Kansas City Expressway, including the Route 110 designation and the C-KC logo on every route marker between Hannibal and Kansas City.^[4]

The sign inside Missouri consists of three letters, CKC. The first C is shaded red.

IL 110 crosses into Illinois from the Mark Twain Memorial Bridge east of Hannibal. It follows Interstate 72 (I-72) east to I-172, then runs north with I-172 to IL 336 around the city of Quincy. Both routes run north to Carthage, where IL 110 and IL 336 join with U.S. Route 136 (US 136). All three routes run east to Macomb, where IL 110 then continues north with US 67 to Monmouth. There is a two-mile (3.2 km) stretch of the route in Good Hope, Illinois, where it is reduced from a four-lane divided highway to a three-lane undivided street with a center turn lane.

At Monmouth, IL 110 joins US 34 and runs east to I-74. IL 110 then joins I-74 and runs north to near the Quad Cities, joining with I-80 before joining I-88 eastbound. The two highways continue east to I-88's eastern terminus in Hillside, where IL 110 continues on I-290, terminating at the Circle Interchange near the Chicago Loop.

The Cannon Ball Route was a historic auto trail that ran from Hannibal, Missouri east-northeast to Chicago, Illinois.^[5] The route was included in the 1917 Map of Marked Routes provided by the Illinois State Highway Department, a precursor to the modern-day Illinois Department of Transportation.

This highway routing closely parallels the Hannibal-Quincy to Chicago branch of the Chicago, Burlington & Quincy Railroad. This route stayed west and north of the Illinois River, so this route never had to cross the limited number of Illinois River bridges in 1917.

IL 110 was the designation for what is present-day IL 15 from St. Libory, Illinois to just south of Addieville, where it meets up with IL 160. During the World War II years, IL 15 was part of what is now IL 160, and the section from St. Libory to Addieville was IL 110. The number was dropped in favor of US 460; the present IL 15 and IL 160 routings came in the mid-1960s.

Raven Road in Washington County is a stub of the former IL 15, and that intersection was the eastern terminus of IL 110.

Efforts to construct a direct route from Chicago to Kansas City have been in the planning stages since its exclusion from the Interstate Highway System in the 1950s. These efforts have been led by the Tri-State Development Summit, an economic development group for western Illinois, southeastern Iowa, and northern Missouri.^[6][7] The proposed highway took different forms over time: a 1989 study found that a full, limited-access tollway running from Kansas Turnpike at Kansas City to the Indiana Toll Road at Gary or Tri-State Tollway near the Joliet area would cost $2–$2.5 billion, if funded entirely by private investors.^[8]

In a joint resolution between the Illinois House and Senate in late May 2010,^[9] an expressway project connecting Chicago-to-Kansas City was named Illinois Route 110 (IL 110). The path, 532 miles (856 km) in total,^[10] follows parts of the existing IL 336, I-88, I-172, I-72, I-74, US 136, US 67 and connect the cities of Quincy, Macomb, Galesburg, a number of communities of the Chicago metropolitan area, including Chicago itself on I-290.^[6][7][11]

In 2010, signs were posted with the "CKC" banner above the IL 110 sign. The Illinois Department of Transportation erected 470 IL 110 (CKC) signs at a cost of $94,000.^[3][12]