There are definitely regional differences in driving style. It depends in part on whether people who grew up there were required to have formal instruction, but also just learning the local style.

Driving in Boston is like driving in LeMans. You move at top speed, close together, and glancing to the left or right is taken as a sign of weakness. But traffic moves very efficiently because individual motorists know how to comprise a cohesive, dynamic flow. Natives are brought up knowing how to navigate narrow, weirdly designed roads like Storrow Drive, with its surprise lane changes and sharp curves, at a good clip.

Driving in the Northwest, to gently counter MastaHanky, is the polar opposite. Motorists are oblivious to one another and overall traffic flow, so backups are endemic. They're reading newspapers or doing their eyelashes in there. And left-lane banditry (blithely cruising in the overtaking lane at or below the speed limit) is a way of life here. It's the only place in the country I've heard drivers defend their right to squat in the fast lane at 55-60 mph, even when it plugs up traffic flow and causes desperate right-side passing behind them, or even accidents. I think Seattle is actually the most dangerous place to drive in the US because of this defiant individualist mentality from motorists who aren't that skilled (no driver's ed required here; even auto safety inspections are not required). Every once in awhile some suburban mom in a hulking SUV mows down a couple of children because she was eating a bowl of cereal while driving or something.

PS. I have been to 46 states... all but HI, AK, ND and MT.