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9. Washington, D.C.

9. Washington, D.C.
Congestion score: 16.4
Population density: 997.1 people per sq. mile (18th highest)
Average commute time: 34.5 minutes (2nd highest)
Percentage driving to work: 76% (6th lowest)

Just 76% of all Washington, D.C. area commuters used a private vehicle to get to work in 2011, less than nearly all other large metropolitan areas. And as many as 14.8% of commuters used public transit—among the most in the nation. But with the Washington area among the nation’s most congested, the average commute time to work was 34.5 minutes—behind only the New York metro area. Traffic congestion did improve in 2012, when the city received a congestion score of 16.4—down from 19.9 the year before. The lower score indicates that drivers are traveling closer to “free flow” speed during peak hours, even as large stretches of Interstate 95 and the Capital Beltway ranked among the worst congestion corridors in the nation.

The 10 U.S. cities with the worst traffic

Last year, the average American driver wasted 38 hours sitting in

traffic. While the occasional traffic jam inconveniences most drivers,

some unlucky people live in the nation’s most congested cities. To determine the 10 cities with the

worst traffic, 24/7 Wall St. reviewed figures published by INRIX, a

traffic information and services group. The INRIX scorecard assigns an

index score for the 100 largest metropolitan statistical areas, and

individual road segments within those areas. Scores are functions of the

percentage difference between road segments’ uncongested (or “free

flow”) travel time and the calculated travel time on the roads during

peak hours. 24/7 Wall St. also reviewed population density from the 2010

Census, as well as travel time and commuting methods for each metro

area from the Census Bureau’s 2011 American Community Survey. All data

used were the most recent available. These are the 10 cities with the

worst traffic.