An interstate shield is a red, white, and blue shield that carries the word "Interstate" the state name, and route number (fhwa.dot.gov). It is the official route marker for the United States Interstate Highway System, trademarked by the American Association of State Highway and Transportation Officials.
The numbering system explained:
"Routes with odd numbers run north and south, while even numbered run east and west. For north-south routes, the lowest numbers begin in the west, while the lowest numbered east-west routes are in the south. By this method, Interstate Route 5 (I-5) runs north-south along the west coast, while I-10 lies east-west along the southern border (fhwa.dot.gov)."
Origin
The planning for the “Dwight D. Eisenhower National System of Interstate and Defense Highways, also known as “The Interstate System”, started in the late 30’s.
It wasn't until President Eisenhower signed the Federal-Aid Highway Act of 1956 that the Interstate system needed its own brand of signs to differentiate it from U.S. state highway marker shields. (examples pictured below)
Image by Kurt Kohlstedt
After the signing of the Federal-Aid Highway Act of 1956, AASHTO (American Association of State Highway and Transportation Officials, referred to as AASHO in the 50's) commissioned designs for an interstate marker. A flood of 76 designs were sent from AASHTO's member states. Most traffic engineers went with a more practical approach to the sign design. A big letter “I” was the theme throughout the submissions, but some featured an eagle, a star, and even a huge map of the United States.
Following careful consideration, and after reviewing dozens of design proposals, a design was approved on August 14, 1957. The winning design was submitted by Texas traffic engineer, Robert Oliver. He picked a shield symbol as a sign of federal authority and submitted the design in black and white because he didn’t know colors were allowed. About ten years later, on September 19, 1967, Trademark Registration 835,635 was issued for the Interstate Shield.
Interstate Shield Design Proposals
State submission: Texas - Image by Kenny Malone via wlrn.org
State submission: Unknown - Photo by Greg Castillo Photoshopped by Kenny Malone via wlrn.org
State submission: Unknown - At the time, the US had yet to add Hawaii and Alaska.
Image by Kenny Malone via wlrn.org
State submission: Florida
Image by Kenny Malone via wlrn.org
The winning Interstate Shield design by retired traffic engineer Richard Oliver of Texas. Image by Kenny Malone via wlrn.org
The official trademarked Interstate Shield we know today. The final design is a combination of the State of Missouri's and Richard Oliver's design.
Image by Kenny Malone via wlrn.org
Where Interstate Shields are Displayed.
On Reassurance Markers
On Highway Guide Signs
On Mile Markers
On Highway Lanes
Image by Federal Highway Administration via safety.fhwa.dot.gov.
How We Make Interstate Route Shields
First, we digitally print the interstate shield graphic on to 3M Diamond Grade Reflective Sheeting.
Next, the reflective sheeting is laminated using 3M ElectroCut Film 1170.
After lamination, the graphic is cut out in order to be applied onto a metal blank.
The graphic is either directly applied to a highway guide sign, or applied to a DOT-spec metal blank.
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