August 14
| 1957 | After months of consideration and viewing nearly 100 suggested shapes, sizes, and variations of Interstate route markers, AASHO's Route Numbering Committee presents its recommendations to the Executive Committee, which endorses the proposed Interstate shield and forwards the plan to the Committee on Administration. (The final version was a combination of proposals by Missouri and Texas.) The committee adopts the Interstate shield, as well as a purpose and policy statement for numbering the Interstate System (using a mirror image of the numbering plan for U.S. routes). Administrator Bertram Tallamy (a member of the Executive Committee) formally approves the plan on September 10. |
