Why people do left hand driving in united states   

well boopathy thank you for your reply .
well what do you do??

It seems that there were very practical reasons for the United States and France to start driving on the right hand side of the road in the 1700s...
According to this website, http://www.i18nguy.com/driver-side.html , "Seven hundred years ago, everybody used the English system. In the Middle Ages you kept to the left for the simple reason that you never knew who you'd meet on the road in those days; you wanted to make sure that a stranger passed on the right so you could go for your sword in case he proved unfriendly..."

So what made the United States switch, the same site goes on to say: in the late 1700s, "when teamsters in the United States and France began hauling farm products in big wagons pulled by several pairs of horses. These wagons had no driver's seat; instead the driver sat on the left rear horse, so he could keep his right arm free to lash the team. Since you were sitting on the left, naturally you wanted everybody to pass on the left so you could look down and make sure you kept clear of the other guy's wheels. Ergo, you kept to the right side of the road."

So... that provides the explanation you sought...

As someone in the United States, let me tell you that I do not know how I would manage if I had to drive on the left... The streets are constructed with street lights, stop signs, etc. with driving on the right in mind. And since I was young I have never known anything else...

It is fun to speak with someone who has a completely different view of the road.

Oh thanks very much. You have explained well with the history of its origin.