Missouri Supplental Routes are officially designated as "State Secondary Roads". They are roads within the state of Missouri designated with letters. Supplemental Routes were various roads within the state which the Missouri Department of Transportation were given to maintain in addition to the regular state routes. The three types of roads designated as supplemental routes are: Missouri, named after the Missouri Siouan Indian tribe meaning canoe, is a Midwestern state of the United States with Jefferson City as its capital. ...

• Farm to market roads
• Roads to state parks
• Former alignments of US or other state highways

Highway Designations

Various letters (but not all) are used in the designations of these highways. The letters "G", "I", "L", "Q", and "X" are not used. The letter "R" is only used as discussed below. Additionally, some routes are double letters (such as Route AA, MM). Usually, but not always, double letter routes are farm to market roads which end at county roads or are former alignments of other highways.

Additionally, combinations of letters may be used, but always with "A" as the first letter (such as Route AD). The only exception is Route BA found in western St. Louis County. Map of Missouri highlighting St. ...

Supplemental routes which connect with state parks begin with the letter "R" (such as Route RB).

These routes rarely run for more than a few miles, though they may cross county lines. But at other highway crossings, they usually (but not always) change names. For example: In Greene County, southbound State Route J crosses U.S. Highway 60 and becomes State Route NN. But when State Route MM crosses Missouri State Route 360, it remains MM, only changing into State Route B when crossing Interstate 44. Greene County is a county located in the state of Missouri. ... US 60 is an east-west United States highway, running 2,670 miles (4,300 km) from Virginia to Arizona. ... Missouri State Route 360 is part of the James River Freeway, a freeway around the southern part of Springfield connecting Interstate 44 and U.S. Highway 60. ... Interstate 44 is an interstate highway in the central United States. ...

Signage

Supplemental routes are signed by black letters on a white background with a black border. Occasionally they will be marked with banners such as EAST, WEST, or END, but this is extremely rare. There are no business or bypass routes for the roads, however two examples exist of spur routes: Spur Route N in Cedar County and Spur Route Y in Montgomery County. A spur is a metal instrument composed of a shank, neck, and prick, rowel (sharp-toothed wheel), or blunted end fastened to the heel of a horseman. ... Cedar County is a county located in the state of Missouri. ... Montgomery County is a county located in the state of Missouri. ...