When people think about aggressive or discourteous drivers, images of raging New York cabbies or over-stressed Los Angeles commuters come to mind.

But our preconceptions are wrong.

Houston, Tex. has the least courteous drivers in America, according to the newly released Driver's Seat Road Rage Survey from AutoVantage, which ranks American cities based on road etiquette and aggressive behavior.

AutoVantage, along with partner firm Prince Market Research, surveyed 2,500 drivers in 25 major metropolitan areas who drive in traffic more than three days a week.

While Houston and Atlanta may be America's road rage capitals, the survey also found that for the second year in a row, Portland, Ore. has the most courteous drivers.

Compared to AutoVantage's first survey in 2009, drivers in Baltimore, Washington D.C., and Boston have become much less courteous; dropping 20, 16, and 12 spots respectively. Baltimore's fall from driving civility is the most staggering, as this year's third least courteous city was actually last year's third most courteous city.

Conversely, drivers in Minneapolis, Dallas, and Detroit became much more courteous improving 15, 11, and 9 spots respectively.

Also of note is New York City's move towards driving civility. The 2013 road rage capital managed to move out of the bottom five entirely in this year's survey.

Here are the five American cities with least courteous drivers, according to AutoVantage:

Rank 2014 2013

1. Houston New York City

2. Atlanta Dallas

3. Baltimore Detroit

4. Washington D.C. Atlanta

5. Boston Minneapolis

For some additional perspective, here are the five cities with most courteous drivers:

Rank 2014 2013

1. Portland Portland

2. Pittsburgh Cleveland

3. St. Louis Baltimore

4. San Francisco Sacramento

5. Charlotte Pittsburgh