In the United States, driver's licenses are issued by each individual state, territory, and the District of Columbia rather than by the federal government due to federalism. Drivers are normally required to obtain a license from their state of residence and all states recognize each other's licenses for non-resident age requirements. A state may also suspend an individual's driving privilege within its borders for traffic violations. Many states share a common system of license classes, with some exceptions, e.g. commercial license classes are standardized by federal regulation at 49 CFR 383. Many driving permits and ID cards display small digits next to each data field. This is required by the American Association of Motor Vehicle Administrators’ design standard and has been adopted by many US states. According to the United States Department of Transportation, as of 2018, there are approximately 227 million licensed drivers in the United States.