Section 21658.
Cal. Vehicle Code - VEH § 21658.
in effectWhenever any roadway has been divided into two or more clearly marked lanes for traffic in one direction, the following rules apply:
(a)
A vehicle shall be driven as nearly as practical entirely within a single lane and shall not be moved from the lane until such movement can be made with reasonable safety.
(b)
Official signs may be erected directing slow-moving traffic to use a designated lane or allocating specified lanes to traffic moving in the same direction, and drivers of vehicles shall obey the directions of the traffic device.
Source: CA Legislative Counsel Bulk DataURL: https://downloads.leginfo.legislature.ca.gov/pubinfo_2025.zipFetched: 6/27/2026