What distinguishing feature identifies a driver's license for individuals under 21?

A vertical orientation is a distinguishing feature of driver's licenses issued to individuals under 21 in Wisconsin. This design choice serves a functional purpose: it helps law enforcement and others quickly identify the age of the driver at a glance. The vertical layout makes it immediately recognizable that the license holder is under the legal drinking age of 21, thus aiding in the enforcement of age restrictions for alcohol sales.

The other design elements, such as color coding or photograph presence, may not consistently indicate age and do not serve the same immediate identification purpose. Horizontal licenses, which are generally designated for those 21 and older, reinforce the use of orientation as a clear indicator of age in this context.