Speed limit sign
A black and white rectangle showing the highest speed allowed on that stretch of road, in miles per hour.
How to read it
The limit it shows is set by law, ordinance or regulation, or by the responsible agency after an engineering study, and the MUTCD requires it in multiples of 5 mph. The signs stand where one limit changes to another. Pennsylvania's manual adds that the posted figure is the maximum legal speed under ideal conditions.
Also searched as: speed limit.
Rules vary by state and country. This explains the sign's standard meaning in the U.S. Manual on Uniform Traffic Control Devices; it isn't legal advice.
Where the number comes from
The MUTCD requires any speed zone other than a limit set by statute to rest on an engineering study, including an analysis of how fast free-flowing vehicles actually travel. The 11th edition of the Manual, published in December 2023, expanded the criteria for setting speed limits in different contexts and environments.
Read next
- Next in Road signsOne way signAn arrow sign reading ONE WAY. Traffic on that street or road may travel only in the direction of the arrow.
- The same shape in Pottery and porcelain marksHull marksHull is the mark of the Hull Pottery Company of Crooksville, Ohio, which made stoneware, kitchenware, art pottery and florist ware from 1905 until it closed in 1986. Its marks include an H in a diamond or circle, Hull Art U.S.A. with a letter and number, a flowing script Hull from 1949 and a lower-case hull from the 1960s.
More road signs
The same shape elsewhere
Browse symbols drawn with letters and numbers.
Sources
- MUTCD 2009 Edition, Chapter 2B: Regulatory Signs, Barricades, and Gates, MUTCD 2009, Part 2, U.S. Federal Highway Administration, Section 2B.13
- Pennsylvania Driver's Manual, Chapter 2: Signals, Signs and Pavement Markings, Pennsylvania Department of Transportation, pp. 10, 12
- Official Florida Driver License Handbook, rev. 08/2023, Florida Department of Highway Safety and Motor Vehicles, p. 48
- The Evolution of MUTCD, Updated December 2023; after H. Gene Hawkins, Jr., ITE Journal, 1991–1994, U.S. Federal Highway Administration, Part II, 2023, 11th Edition
Researched, edited and approved by Rory Hansen before publishing. Last reviewed September 25, 2026. How we research
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