That dubious honor goes to .. Honolulu.
Commuters in the Hawaiian paradise capital spent some 58 hours not moving in their cars last year, said the study which nevertheless put LA in second place, with San Francisco and New York not far behind in the traffic nightmare stakes.
Overall there was at least some good news: traffic congestion was down by 30 per cent overall in America, according to the fifth Annual INRIX Traffic Scorecard.
Traffic congestion was down not only in the United States.
"The declines in traffic congestion across the US and Europe are indicative of stalled economies worldwide," said INRIX boss Bryan Mistele.
"In America, the economic recovery on Wall Street has not arrived on Main Street. Americans are driving less and spending less fueled by gas prices and a largely jobless recovery," he added.
But in the top 10 US cities for traffic chaos, drivers spent an average 40 hours last year not moving, peaking at 60 hours annually on the nation's most gridlocked roads.
In what might surprise some, the Pacific island state of Hawaii -- think palm trees, white sands, huge rolling surf -- is actually home to some of the worst gridlock in America.
LA was second with motorists idling for 56 hours, followed by San Francisco on 48 hours. The rest of the top 10 were: New York; Bridgeport, Connecticut; Washington, DC; Seattle; Austin, Texas; Boston, Massachusetts; and Chicago.
The study also listed the top 10 worst traffic corridors, or stretches of gridlocked highway.
Top horror gridlock prize went to a 13-mile stretch of the San Diego Freeway in Los Angeles, followed by a 16-mile stretch of the Long Island Expressway in the New York suburbs.
The rest of the top 10 went to: Los Angeles; New York; Los Angeles; New York, Los Angeles; New York; with Pittsburgh sneaking into 9th place and San Francisco rounding out the traffic big leaguers.
The overall drop in congestion followed modest increases in 2009 (one per cent) and 2010 (10 per cent). The last similar decline was in 2008, the year of the financial crash, when traffic congestion plummeted 34 per cent.
Full details can be seen at: http://www.inrix.com/pressrelease.asp?ID=156.