FHWA Series fonts
The FHWA Series fonts (often informally referred to as Highway Gothic) are a set of sans-serif typefaces developed by the United States Federal Highway Administration and used for road signage in the U.S., Canada, Turkey, Mexico, Australia, Norway, Spain, Venezuela, the Netherlands, Brazil, Argentina, China, Taiwan, Malaysia, Indonesia, India, Mongolia and New Zealand. The fonts were created to maximize legibility at a distance and at high speed. Versions known as Highway Gothic or Interstate, which are for sale to the general public, include punctuation marks based on a rectangular shape. However, on signage, the official FHWA Series punctuation is based on a circular shape.
The set consists of seven fonts: "A" (the narrowest), "B", "C", "D", "E", "E(M)" (a modified version of "E" with wider strokes), and "F" (the widest). The fonts originally included only uppercase letters, with the exception of "E(M)", which was used on large expressway and freeway guide signs.
The typefaces are officially defined by the FHWA's Standard Alphabets for Traffic-Control Devices, originally published in 1945 (reprinted 1952). Changes to the specifications were published in 1966, 1977, and 2000. The 2000 specifications differ from earlier versions in the shapes of a few letters and in the inclusion of lowercase letters for all alphabet series.
FHWA Series A, B, C, D, E, and F were developed by the Public Roads Administration (which later became FHWA) during World War II. Draft versions of these typefaces were used in 1942 for signs on the Pentagon road network. In 1949–50, as part of a research program into freeway signing carried out by the California Department of Transportation, Series E Modified was developed from Series E by thickening the stroke width to accommodate button reflectors for ground-mounted signs, while a lowercase alphabet was developed to allow mixed-case legend (consisting initially of Series D and lowercase letters) to be used on externally illuminated overhead signs. The lowercase letters, paired with Series E Modified, later became the basis of a national standard for mixed-case legend on freeway guide signs with the 1958 publication of the AASHTO signing and marking manual for Interstate highways.
Series "A" has been officially discontinued in the U.S., 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, was expected to replace the FHWA series on some new signage. However, the FHWA has announced its intentions to rescind the interim approval for use of Clearview and maintain the use of the FHWA series in the 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 F is most commonly used on U.S. speed limit signs, although older signs often use narrower fonts. Signs that show the names of streets usually feature white Series A, B, C or D letters (which may either have all capital letters or a combination of capital and lowercase letters) on a green background (which can also be substituted for other colors, such as blue or red). Georgia uses both Series C and D fonts for the Interstate highway signs.
By the mid-1990s the FHWA series of typefaces was used as a source of inspiration for a multi-weight print typeface designed by Tobias Frere-Jones of Font Bureau. Frere-Jones made accommodations for smaller print reproduction and Font Bureau released the face under the name Interstate. It has been adopted by many companies for branding; for example, NBC used it for NBC Sports graphics packages from 1997 to 2006, and TV Guide uses the typeface on its cover. Also, The Weather Channel utilized this typeface extensively, both on its weather maps and for its local forecasts. The logo of the premium cable channel Epix also uses a lowercase version of this typeface. The New York Mets use this typeface at Citi Field. The gossip magazine InTouch is now using this typeface since 2012. Films like 8 Mile also use this font.
The FHWA typefaces are also used on road signs in Canada (The province of Ontario used an in-house modified version until the late 1980's that featured slightly different characteristics, such as flat-top numeral 3's and numeral 1's without a serif), Peru (under different series labels), Australia, New Zealand, Indonesia, Malaysia, Mexico and other countries. Still others use typefaces that are either derived directly from the FHWA series or very similar in appearance. There are a few of them in South Africa, Lesotho, the Philippines, and Thailand.
In mainland China, the font has been adopted for use in signs on new Chinese national expressways, beginning with the Jingjintang Expressway, which uses the font for the first 17 kilometers in Beijing. In Taiwan, the FHWA series of typefaces are also used on English text.
Indonesia formally using the typeface at 9 September 1993, regulated by Ministry of Transportation's law No. 62 year 1993.
In Spain, series E is the base for Autopista typeface, used in motorways and freeways.
States using Highway Gothic
|Alaska||Some Clearview signs; current ADOT guidance as of 6/1/13 is to use FHWA series only.|
|Florida||The toll roads in Orlando use Clearview.|
|Georgia||Uses Series C and D for the Interstate highway signs, slowly replacing them with Series E.|
|Illinois||Few of them in the Chicago area, and all of I-55 and I-57. But slowly replacing them with Clearview|
|Kansas||The Kansas Turnpike Authority is changing its signs to Clearview.|
|Massachusetts||Massachusetts MUTCD expressly forbids Clearview.|
|Michigan||Few of them along I-94, I-69, I-196, and US 24. 80% of the state now uses Clearview. The old FHWA signs includes underlined cardinal directions.|
|Missouri||Missouri has started using Clearview on blue and white attraction signs.|
|Nevada||US 395 in Reno uses Clearview|
|New Mexico||Highways in district 5 use Clearview.|
|New York||NYSTA uses Clearview for some signs.|
|Utah||Legacy Parkway uses Clearview|
- Loutzenheiser, D.W. "Design of signs for the Pentagon road network." Proceedings of the Highway Research Board, 1943, pp. 206-35.
- Forbes, Theodore W, Moskowitz, Karl, and Morgan, Glen. "A comparison of lower case and capital letters for highway signs." Proceedings of the Highway Research Board, 1950, pp. 355-373.
- Moeur, Richard (2005-04-22). "Sign Typefaces". Manual of Traffic Signs. Retrieved 2006-05-18.
- Yaffa, Joshua (August 11, 2007), "The Road to Clarity", The New York Times Magazine, retrieved 11 August 2007.
- Kehrli, Mark R. "IA-5.31 - Clearview - Grays Harbor County, WA (DENIED)". Federal Highway Administration. Retrieved April 25, 2014.
- "Chapter 8: Letras y números para señales". Manual de dispositivos para el control del tránsito en calles y carreteras (in Spanish) (5th ed.). Mexico: Secretaría de Comunicaciones y Transportes. 1986. pp. 425–486. ISBN 968-803-140-2.
- Minister of Transportation Regulation Number 62 of 1993
- Standard Alphabets for Traffic Control Devices from the United States Federal Highway Administration (PDF)
- Sign Typefaces from the Manual of Traffic Signs
- roads UK—Fonts for many national road systems, including the FHWA series for the US.
- Road Geek—freeware fonts, created by Mike Adams and based on all of Series B through F, plus additional fonts based on highway signage around the world.
- FontSpace's Highway Category - Includes Mike Adams' fonts plus others (some personal use only, some commercial friendly).
- Public domain fonts used on road signs.
- Interstate from Font Bureau
- Blue Highway - Ray Larabie's free version