(a) Cities with population under 1 million
(b) Cities with population over 1 million
NOTES: An eligible driver is someone 16 years and older who is eligible for a driver's license. The cities shown represent the 50 largest metropolitan areas, as well as others chosen by the states sponsoring the study. For a detailed explanation of the formulas used, see the source document.
SOURCE: Texas Transportation Institute, Urban Roadway Congestion Annual Report (College Station, TX: 1998).