The 13 cities where you will encounter the worst traffic in America

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Congestion is getting worse every year in the United States.

In fact, the average US commuter spends 42 hours stuck in traffic a year, according to a report by the Texas Transportation Institute. Congestion is also a big reason why auto and tech companies are pouring money into everything from car-sharing to autonomous driving.

TomTom, a navigation and mapping company, ranked US cities that have the most traffic congestion in its 2017 Traffic Index.

After collecting data over a nine-year time span, TomTom measured the extra travel time experienced by drivers over an entire year. TomTom assessed 189 cities overall and gave each a congestion score out of 100. Each percentage represents how much extra travel time it took on average to make any trip, anywhere in the city.

Here are the most congested cities in the US:

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13 US cities with the worst traffic
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13 US cities with the worst traffic

13. Baton Rouge received a score of 26%, meaning it took commuters 26% more time to travel anywhere in the city. This was a 3% increase from 2016.

(Photo by Chris Graythen/Getty Images)

12. Atlanta edged ahead of Baton Rouge with a score of 27%, also a 3% increase from the year prior.

(Photo by Prince Williams/Getty Images)

11. San Diego had the same exact traffic score as Atlanta at 27%, also a 3% increase from 2016.

 REUTERS/Mike Blake 

10. Boston received a score of 28%, a 3% increase from the year prior.

(Photo by Joanne Rathe/The Boston Globe via Getty Images)

9. Washington D.C. barely edged out Boston with a score of 29%, a 3% increase from the year prior.

 (Photo by Ricky Carioti/The Washington Post via Getty Images)

8. Honolulu received a score of 29%. That's the same as Boston, but Honolulu has more congestion in the morning. Honolulu's traffic score was the same as the year prior.

(Photo by Francis Dean/Corbis via Getty Images)

7. Portland also received a traffic score of 29% overall, a 3% increase from the year prior. But Portland has a much higher concentration of traffic in the afternoon than Boston or Honolulu.

(Photo by Shawn Patrick Ouellette/Portland Press Herald via Getty Images)

6. Miami received a score of 30%, a 2% increase from the year prior.

REUTERS/Joe Skipper/File Photo

5. San Jose got a traffic score of 32%, a 2% increase from 2016.

(Photo by David McNew/Newsmakers)

4. Seattle received a traffic score of 34%, a 3% increase from the year prior.

(Photo by George Rose/Getty Images)

3. New York actually barely edges out San Jose with a traffic score of 35%, a 2% increase from last year.

REUTERS/Adrees Latif 

2. San Francisco has a high traffic score at 39%, a 3% increase from 2016.

(Photo by: Education Images/UIG via Getty Images)

1. But it's probably no surprise that Los Angeles is the most congested city at 45%, a 4% increase from last year.

 REUTERS/Bob Riha Jr 

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