Sandy P., Knucklehead, John M.,

Think map scales. I believe that the US Army first used metric measure (temporarily) in Europe during WWI. There is still no absolute universal for maps but given the high level of coordination of US forces with other forces in the world for the past 60 years I would imagine that the US ground forces adopted metric in order to reduce confusion. All the US military maps that I remember from the early 60′s were metrically scaled. Using different scales produces different coordinates – very embarassing wrt directing artillery fire.