Why are American soldiers called GIs?

Why are American soldiers called GIs?

The reason behind this name is not totally clear, but the most widely believed theory dates back to the beginning of the 20th century, when the letters ‘GI’ were stamped on military trash cans and buckets to show they were made of galvanised iron. The theory goes that it was then used to refer to all things related to the army in World War I, but the meaning of the letters changed to ‘government issue’ or ‘general issue’. By the time World War II occurred, soldiers were referring to themselves as GIs. US toy company Hasbro created the popular GI Joe doll in 1964, and the nickname has stuck ever since.