Is there such a thing as regional etiquette among drivers?

Win Barber of LaPlata advanced my understanding of one regional courtesy when he pointed me toward online descriptions of the Pittsburgh Left, known in other circles as the Boston Left — perhaps even the China Left.

As I read more, this left turn technique began to seem less regional and more globe-girdling. Also getting murkier: Does it involve a courtesy, or is it just another example of aggressive driving?

This was the conversation starter: A letter in my April 14 column (unavailable online) responded to an earlier discussion about the difficulties of making left turns by observing that drivers behave differently in different parts of the country.

Dear Dr. Gridlock:

Regarding people taking left turns ahead of straight-on traffic: I am from Ohio and worked during the 1980s in southwestern Connecticut, near New York City.

I quickly learned that in New England it is an unwritten courtesy to let the first oncoming fellow at a light make a quick left in front of you before you drive straight. I assume this is an old rural custom — I can’t imagine practicing it in a large city like Boston.

Connecticut is officially part of New England, but certainly New York City is like the rest of the United States regarding left turn yields to oncoming traffic.

So, as you sat at a light you had to look in the other fellow’s eyes and decide if he was a New Englander and planned to go left when the light turned green, or he didn’t know the unwritten rule and would wait for the oncoming traffic to clear before he turned left.

I’ve often wondered how many accidents are due to regional courtesies that the other fellow didn’t know about.

Andy Marmorstein, Reston

So I asked travelers if they were aware of such regionalisms, and said the only one I could think of for the D.C. region was our understanding that we walk left and stand right on Metro escalators.

I do have some responses on that for an upcoming column, but Barber’s note focused on the “unwritten rule” about left turns. The blog postings and newspaper accounts that he led me to suggest that drivers in Pittsburgh think they developed the technique in which a driver waiting at a red light to make a left steps on the gas as soon as the light goes green and cuts in front of oncoming traffic.

This technique got a lot of attention in 2006 when Pittsburgh Steelers quarterback Ben Roethlisberger was injured in a motorcycle crash, but purists said the other driver wasn’t really making a classic Pittsburgh Left since the light had been green for a while.

Meanwhile, Boston drivers claim the turn technique as their own. It shows up in the Boston Driver’s Handbook. (The subtitle “Wild in the Streets” suggesting its less than serious approach to traffic rules.)

But on some blogs, commenters say the quick left is common in traffic-choked Chinese cities.

But is anyone, anywhere really being courteous?

There are two possibilities: First is the one that Marmorstein suggested in his letter, that the oncoming drivers are willing to give one turning car a break before they proceed. Second is the one proposed by Pittsburgh drivers, who say it all started because left-turning drivers didn’t want to hold up the straight-ahead traffic behind them at the intersection, so they turned quickly.

After years of reading your letters about discourtesy on the roads, I’m not sure I can adopt such a rosy outlook about drivers anywhere. In fact, many drivers who practice the technique simply say it’s the only way to deal with urban congestion. Many straight-ahead drivers facing the rapid left-turner say it really annoys them.

And I have the sinking feeling that many of you reading this will write back to claim the technique as the D.C. Left, in honor of the trick driving you’ve seen in our region.