R.E.O. are the initials of Ransom Eli Olds. He was responsible for the success of the Curved Dash Olds, but was forced out of his own company for resisting change. Soon after leaving, in January of 1904, Ransom Olds formed a new company to manufacture automobiles and trucks.
When he left Oldsmobile, Ransom Olds sold his name – but not his initials. He called his new car a Reo saying it was a “chip of [sic] the old block”. The first one was completed by the end of 1904. He showed it a few months later at the 1905 New York Automobile Show. By 1906, Reo sales easily surpassed Oldsmobile. In 1907, Reo ranked 3rd in U.S. auto sales.