Minimum Speed 40 mph Traffic Sign - Official R2-4 Regulatory Sign #1905012 (License: Personal Use)

The R2-4 sign is a standardized U.S. regulatory traffic sign defined in the Manual on Uniform Traffic Control Devices (MUTCD), mandating that drivers maintain a minimum speed of 40 miles per hour. Its high-contrast black-on-white design ensures visibility and compliance, especially in areas where slower speeds could disrupt traffic flow or increase collision risk. The sign is typically mounted on overhead gantries or roadside posts along multi-lane highways.

Used on controlled-access highways, expressways, and high-speed rural roads where maintaining forward momentum is critical for safety and efficiency; targets drivers seeking legal speed requirements or studying traffic signage standards.