I have also been asking this very same question for years now and still cannot get a sensible answer. Have you had any response so far?

The reason for this is found in our country's ripe history, when slavery was legal. Women would have a hand maid (either a slave or a less prominent women)that would dress them. It is easier to put on shirts if the buttons are on the right side since most people are right handed and so for someone else to put on your shirt then it is easier if the buttons are on thier right side, your left. Having buttons on the left therefore was a sign of affluence and soon all womens' shirts had buttons on the left. Men did not have someone to dress them therefore there buttons remained on the right while the womens' migrated.

It is interesting to me to note that buttons and zippers on men's shirts and Jackets made in former British colonies Canada and Cyprus are reversed from the American order. I wonder, does that mean that most people in those countries were left handed? Maybe the English sent all the left handers to those colonies and all right handers to what was to become the USA. What about the buttons on shirts in, Say, Turkey, or China? Maybe the USA is the only place that it is done for men on the right and women on the left.

Do you know when the left side/right side button fashion began? I didn't think that many people had clothing with buttons until the 1800's. Do any pictures(art) show R/L side buttons in the 1700's?

I have always been told that it dated back to when men usually carried swords. Since most people are right handed (and therefore hold their sword with their right hand), the sheath would be fastened to the left hip. When shirts were made for men, the buttons were attached to the right side so that when the sword was drawn, it wouldn't catch on the overlap between the button and hole sides of the shirt. Women didn't carry swords, so their shirts didn't need it.

A while ago I pondered this same question, and decided that the buttons must be on the opposite side for men and women in order to make it easier for them to UNdress each other.

ha ha i like the answer about buttons being on the opposite sides to make it easier to undress each other.

http://www.ehow.com/facts_5138878_do-mens-shirts-button-differently.html

I have also heard that in France Napoleon ordered that all women's shirts be buttoned on the opposite side because women use to stick their hands in their shirts to mock him. With the buttons on the opposite side, women could no longer mock him.

To put further fuel to this question,why is it that button holes are vertical until the last one that sometimes is horizontal/

It is my unqualified opinion that since not everyone is the same (some are thin while others are portly with the rest of us somewhere in the middle) shirts are of differing sizes, thus differing lengths, thus the number of buttons down the front varies. The bottom-most button hole being turned 90 degrees would allow someone who was rather portly and could not "see" the end of their shirt or a thinner man dressing in low light such as before dawn could use the tactile cue of the sideways button hole to be sure he had all of his buttons buttoned and be presentable without having to actually see them and worry he appeared slovenly. This may have been borrowed from military uniform manufacturing (or vice-versa) as a soldier could be severely reprimanded for "being out of uniform" for missing his last button. They often had to dress at a moments notice and had to be certain they were in compliance or face disciplinary action. None of this is based on any facts i have found, simply how i think it probably evolved.

They're designed that way, because when standing/walking side by side, the rule of thumb for a man and a woman is the man should be standing on the right side of the woman. In order to uphold the dignity of each other, the buttons are placed that way so that none could peek the other's bossom/chest in case a button fails or there's an opening due to certain body position.