There is no conclusive evidence as to the exact location and time onions were discovered, but many archaeologists, botanist, and food historians believe the vegetable orientated in central Asia. Onions may have been the earliest cultivated crop; they were easy to grow, transportable, and less perishable than other foods of the time.
As a cool-season vegetable, onions can be grown successfully throughout most of temperate North America. Onions contain sulphuric compounds that make you eyes water, but if they are chilled for thirty minutes before the top is cut off and outer layers are peeled (leaving the root end intact), tearing will be reduced. The root end has the highest concentration of sulphuric compounds. Lemon juice or vinegar will remove the smell of onion from your hands. Chewing parsley or a coffee bean will freshen onion breath.
References: National Onion Association, Texas A&M AgriLife Extension Service.