Speed limit sign: what it means

Speed limit sign: a white vertical rectangle with the words SPEED LIMIT and the number 25 in black
Drawing: DriveQuiz, based on MUTCD sign R2-1. Simplified; real signs follow the FHWA Standard Highway Signs specifications.

The SPEED LIMIT sign shows the maximum speed allowed on that road, in miles per hour. It is a maximum, not a target.

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What it means

MUTCD Section 2B.21: speed limits are set either by state law for a class of road, such as freeways or city streets, or as speed zones based on an engineering study.

It is a regulatory sign, black on white. In the MUTCD color code, black and white both mean regulation (Section 1D.05).

Where you see it

Where a speed limit starts or changes, and repeated along the road. School zones can have their own speed limit signs (MUTCD Section 7B.05).

A common mistake

Treating the number as the speed to drive. It is the most you may do; drive slower in rain, traffic, darkness, curves and where people are walking.

Quick quiz

What does the number on a SPEED LIMIT sign mean?

  1. The maximum speed allowed
  2. The minimum speed allowed
  3. The suggested speed for trucks
Show answer

A. The maximum speed allowed. The R2-1 sign shows the maximum speed limit for that road. Source: MUTCD 11th Edition, Chapter 2B, Regulatory Signs, Barricades, and Gates: Section 2B.21, FHWA; MUTCD 11th Edition, Part 1, General: Section 1D.05, FHWA; MUTCD 11th Edition, Part 7, Traffic Control for School Areas: Section 7B.05, FHWA; MUTCD 11th Edition, FHWA

Compare with

Next in regulatory signs: No U-turn sign. See all regulatory signs or the full road signs list.

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Sources

  1. MUTCD 11th Edition, Chapter 2B, Regulatory Signs, Barricades, and Gates: Section 2B.21, FHWA
  2. MUTCD 11th Edition, Part 1, General: Section 1D.05, FHWA
  3. MUTCD 11th Edition, Part 7, Traffic Control for School Areas: Section 7B.05, FHWA
  4. MUTCD 11th Edition, FHWA. FHWA lists the current version as the 11th Edition with Revision 1, dated December 2025

Sign pictures are our own simplified drawings of the MUTCD designs, which are in the public domain (MUTCD Section 1D.06). Sources and image credits.