Standard Sign Typefaces
The standard typefaces used for highway signs in the US are defined in the "Standard Alphabets for Traffic Control Devices", published by the Federal Highway Administration.
Series A: Discontinued
Series E Modified
The official designations for these typefaces are "FHWA Series B", "FHWA Series C", etc. In recent years, a practice has developed of referring to these standard typefaces as "Highway Gothic". This has caught on to the point where even FHWA occasionally refers to their own typefaces in this manner. However, for clarity, it's probably better to refer to these typefaces with the more correct 'series' name.
Series B through F are the standard typefaces used for most signs. They are variations on a standard style, where B has the narrowest letters (for example, the word "PARKING" on a No Parking sign), and F (rarely used) has the widest letters for a given height. In general, the wider the letters, the greater the distance that the wording can be clearly seen and read.
For many years, the Series B, C, D, E and F typefaces included only all capital letters. In 2004, however, FHWA created and approved lower-case letter designs for all these series of typefaces, and recent changes to the MUTCD have approved the use of lower-case legends for guide sign legends on all classes of roadways.
The lower case loop height for lower case letters is 75% of the upper case height. For example, a lower case 's' is 75% of the height of an upper case 'S'.
Large guide signs installed on freeways and expressways typically use Series E modified upper and lower case lettering. Guide signs on conventional roadways use anything from Series C to Series E Modified depending on available sign width, desired legibility distance, etc.
The reason Series E Modified is called 'modified' is because the letter stroke (width of lines making up letter) is modified to be 20% of the letter height. For comparison, standard B thru F letters have a stroke width approximately 13-18% of height.
Button copy lettering has been in use for decades across the country for large expressway and freeway guide signs. "Button copy" is a generic term for highway sign characters which are made out of enameled metal, with small white circular reflectors (the 'buttons') inlaid in the surface to provide retroreflectivity at night. Button copy is no longer manufactured in the United States, as it could no longer compete cost-wise with newer computer-cut reflective sign letters. Arizona was the last state to specify button copy sign lettering, but stopped ordering new button copy signs in late 2000. Button copy typefaces closely resemble standard FHWA Series D, E, and Series E modified typefaces, except for minor differences to accommodate the inlaid reflectors.
Another typeface under development for highway signage is known as Clearview. This typeface has shown promising results in real-world legibility conditions, and as of 2004 is authorized for use (with FHWA approval) on guide signs and other signs where the lettering is lighter than the sign background.
For more information, see the FHWA webpage on Clearview .
The National Park Service uses a font known as Clarendon for sign legends. This typeface is very similar to the standard font known as Clarendon. This font is distinctive (for a highway sign font, that is) for using serifs.
Research has shown that Series E modified and Clarendon score approximately the same in legibility tests for most drivers.
Highway Sign Font and Image Vendors
1952 Standard Alphabets, including geometric layout info for Series A through F (3.0 MB PDF)
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Updated 24 August 2014 (coding)Scripting: Richard C. Moeur