Driver Holding His Car's Test Card as It Proceeds Along the Safety Lane During a Checkup at an Auto Emission Inspection Station in Downtown Cincinnati, Ohio. Since January, 1975, All Vehicles in the City Are Being Checked Once a Year on Safety Requirements Previously They Were Tested Semi-Annually.
the Change Was Made Because of the Addition of Carbon Monoxide and Hydrocarbon Emissions Testing on Light Duty, Spark Ignition Powered Motor Vehicles 09/1975. Photographer: Eiler, Lyntha Scott. Original public domain image from Flickr