This policy requires all CBP land ports of entry to display signs or provide literature informing foreign drivers that speed limits in the United States are measured in miles per hour (MPH), not kilometers per hour (KPH). Drivers are advised to adjust their speed to comply with U.S. traffic laws.
This is particularly important for Mexican drivers entering the United States at Nogales, AZ, where Interstate 19 signage shows a speed limit of 75 without specifying MPH. Many new arrivals mistakenly drive at 75 KPH, which converts to only 46 MPH, creating a potential safety hazard.