1958 publication of the American Association of State Highway and Transportation Officials (AASHTO) signing and marking manual for Interstate Highways. Series "A" has been officially discontinued in the United States due to poor legibility at high speeds, though it continues to be specified for certain signs in New Zealand. In 2004, the FHWA published lowercase letters for all of the typefaces and made changes to the Manual on Uniform Traffic Control Devices, which allows their use. There was an expectation that over the next few decades, the new Clearview typeface, also specifically developed for use on traffic signs, would replace the FHWA series on some new signage. However, the FHWA announced in 2016 that it was rescinding its 2004 interim approval of Clearview in the United States; while existing Clearview signs could stay up, new signs would have to go back to using Highway Gothic. On June 7, 2016, a bill challenging this decision was introduced in the United States House of Representatives, which would have ordered the FHWA to reinstate the interim approval for Clearview. This bill passed as part of the Consolidated Appropriations Act, 2018. The Federal Highway Administration makes no recommendation or endorsement of the Clearview typeface with the reinstatement of their 2004 interim approval. Tobias Frere-Jones designed the typeface Interstate, based on the FHWA series, during the 1990s. Overpass is an open-source replacement for Interstate commissioned by Red Hat. PBS previously used a custom derivative, "PBS Explorer". In 2001, URW++ released the SAA Series typeface, a digitized version of the early FHWA Series typeface. Greece-based Parachute Type Foundry designed the PF Grand Gothik Variable typeface, which also based on the FHWA Series typeface, with OpenType features. Parachute Type Foundry also designed the PF Highway Sans typeface, which also based on the FHWA Series typeface. Tom Oetken designed the free-to-download for commercial and personal use Traffic typeface, which also based on the FHWA Series typeface. Otherwhere Collective designed the Highway VAR variable typeface, which also based on the FHWA typeface. Usage United States Typically, one- or two-digit Interstate, U.S. Highway, and U.S. state route signs use the Series D font for the numbers, while signs with three or more digits use either a narrower font (Series B or C) or have smaller numbers in the Series D font. Series E and F is most commonly used on U.S. speed limit signs, although older signs often use narrower