US road sign R2-1 · regulatory signs
Speed limit
California MUTCD, sign R2-1What does the Speed limit sign mean?
The highest speed allowed on this road, in mph. Drive slower when the road, traffic or weather call for it (CVC 22350, the Basic Speed Law).
How regulatory signs work
They give a rule you must obey. They are rectangular unless the manual names another shape (California MUTCD, section 2B.02); the STOP sign, for example, is an octagon (California Driver’s Handbook, “Laws and Rules of the Road”).
