The vast majority of the street is double-decked; the upper level is intended for local traffic, and the lower level for through traffic and trucks serving buildings on the road (and originally a dock).
It is sometimes cited as a precursor to the modern freeway, though when it was built the idea was that pleasure vehicles would use the upper level. It is the only street in the city that is prefixed with all four cardinal directions, albeit on different parts of its route.
The drive is named for early 20th century Chicago businessman and city planner Charles H. Wacker. The upper level is normally known as Upper Wacker Drive, and the lower level is Lower Wacker Drive. A short part has a third level, sometimes called Lower Lower Wacker Drive or Sub Lower Wacker Drive.