Why are light switches almost always on the left?

Question

I go to high school and this year I had a class where I was always the first one in the door and everyday the teacher would ask me to turn on the lights as I went in.Whenever I walked in I automatically reached for the left every time even though the light switch was on the right. I then got to thinking and realized that in almost every room in my house has the light switch on the left when you walk in the door. (Only two rooms don't and thats because the doors open inward to the left.) I then asked a bunch of my friends and they said that their houses also have there light switches mostly on the left side when you walk in the door. So, I was wondering, Is it just a coincidence that most light switches are on the left or does it actually have some purpose or reason for being on the left? Hope someone has an answer otherwise this is going to be bugging me forever.

Answer 1

Thats odd, cuz all the switches in my house are on the right....

Answer 2

You answered your own question. The rooms with switches on the left have doors that open to the right. The rooms with switches on the right have doors that open to the left. Otherwise, the switch would be behind the door.