The District of Columbia along with the 3-4 counties immediately around it in Northern VA and Maryland are the worst places to drive in the US based on number of accidents per 100K drivers (at least this was the case about 10 years ago when I lived there and I doubt it's changed much since then).
I suppose if you measure bad driving by some other measure then you can make the argument, but I've driven extensively in UT, ID, CA, DC, NV, OR, NY (including NYC), PA, VA, FL, WV, MD, and OH. DC is the worst and it's not close.