May-1-1922. Note of explanation on the map: Minnesota trunk highways, making a 7,000-mile primary road system, are now officially marked with numbers on yellow stars-significant of the North Star State. Reference to this map will guide the user of the system. Grading, gravel-surfacing and paving completed and under contract May 1, 1922 are indicated by the conventions. This should be considered with weather conditions in planning trips. The state trunk highway system has been improved with 228 miles of paving, 1926 miles of gravel surfacing and 2314 miles of permanent grading.
Minnesota Department of Transportation, MnDOT Library