U.S. Route shield
Since the first U.S. Route signs were installed in 1926, the general idea has remained the same, but many changes have been made in the details.
During the meeting, held at the Bureau of Public Roads offices in Washington, D.C., on April 20, 1925, board member Lou A. Boulay of Ohio was credited with suggesting the use of a shield, inspired by that on the Great Seal of the United States, with the letters "U.S.A." and the route number as a route marker.
James (Chief of the BPR's Division of Design and secretary of the Joint Board) and Frank F. Rogers of Michigan sketched a possible implementation of the shield.
James and Rogers presented their shield sketch to the board, and it was approved as a tentative design.
Upon motion by Cyrus Avery of Oklahoma, the board officially adopted the shield proposed at the April 21 meeting, having received general support from the states.
Some members, particularly those from the South, felt it would be difficult to get local support for the U.S. Route System without it, because the states were required to pay for the signage.
The following day, August 4, upon a motion of Robert M. Morton of California, the U.S. shield including the state name was approved without debate.
[1] The original design of the shield was presented in the January 1927 edition of the Manual and Specifications for the Manufacture, Display, and Erection of U.S. Standard Road Markers and Signs, the precursor to the Manual on Uniform Traffic Control Devices (MUTCD), published by the American Association of State Highway Officials (AASHO).
[3] The name of the state erecting the shield was displayed 2 inches (5.1 cm) high in the crown, above the crossbar.
The manual also allowed for the city variant of the shield to be stenciled on culverts and bridge posts.
[3] A standardized block typeface was used to simplify the painting process, to allow illiterate signpainters to be employed.
The 1948 edition of the MUTCD introduced the first change to the U.S. Route shield since its appearance in the 1927 AASHO manual.
The shield shape and size, letter height, and layout was otherwise identical to the prior version.
[5] A supplemental AASHO publication outlining signage and pavement markings on the nascent Interstate Highway System, also published in 1961, included a variant of the shield intended for freeway use (such as for U.S. routes running concurrently with Interstates).
[7] In the 2009 MUTCD, the U.S. Route shield is assigned catalog number M1-4 and is discussed in Section 2D.11.
[8] However, deviations are common, especially in New Jersey, which consistently includes the black background on both U.S. Route shields and state route markers on its guide signs, though inclusion of the background and thinning is being phased out on many new sign installations in New Jersey as of the late 2000s.
Arizona experimented with colors indicating the signed cardinal direction of the highway (orange for north, green for south, brown for east, and blue for west).
