LAS VEGAS - TomTom found that Los Angeles is the number one most-congested city in North American in the latest edition of its Construction Index, which measures traffic congestion.

The new rankings measured traffic congestion between July and September 2012. This index looked at congestion in more than 57 metropolitan areas with a population of greater than 950,000.

On average, trips in Los Angeles take 34% longer when traffic is flowing freely, and 76% longer during the evening rush hour. The average congestion level for all cities in North America analyzed during the period noted previously was 19%. Also, the most recent Congestion Index report found that traffic problems concentrate in western North America, with the top five metropolitan areas all located in that region.

One finding in the Congestion Index is that non-highway congestion is always greater, by at least 9%, than highway traffic.

The top 10 most congested North American cities, ranked by overall Congestion Level, between July and September 2012 are as follows:

1. Los Angeles (34%)

2. Vancouver (34%)

3. San Francisco (33%)

4. Honolulu (31%)

5. Seattle (27%)

6. Toronto (26%)

7. New Orleans (25%)

8. San Jose (25%)

9. Montreal (24%)

10. Chicago (24%)