In 1920, the Babcock Amendment authorized 70 "constitutional route" (CR) highways cris-crossing the state. Until the 1974 modification of the constitution (see section below), these were enumerated in the document itself, though today they are listed in the Minnesota Statutes (§161.114). Still, the general routes cannot be altered or removed without amending the constitution and are therefore somewhat fixed. In many cases, the constitutional route numbers do not match highway numbers. In fact, it has been common for CR highways to be composed of several different trunk highways. When the U.S. Highway system was created in 1926, many of these roads were made up of one or more U.S. highways. Today, they now use a mix of Minnesota state highways, U.S. highways, and Interstate highways.