Agressive driving likely reflect the culture,and local values. I suspect driving practices in many small towns and rural areas in both countries may be quite similar. Many USA cities tend to be larger, and I suspect faster and likely with more agressive drivers. Regardless, driving in both countries is much less stressful than many world areas. On a related note, a few years back, I found Quebec driving (Montreal) to be faster and more agressive (somewhat European). Lately, I have found the local police has tamed drivers down a bit.