Factory finished wood flooring wasn't really a thing before 1940 - 1950. During WWII, a lumber company by the name of Higgins Lumber Company were making navy boats from oak plywood. The owner, Mr. Higgins was trying to find a way to reuse the waste from the manufacturing process so he ended up cutting the wood into 12-by-12s and 9-by-9s. The government at the time had tight constraints on raw materials so the wood had a set price manufacturers could charge for it. To get around this, Higgins started adding a wax finish to the wood which made it a finished product so that the government couldn't restrict it. This business practice inspired other lumber companies who were looking for markets for their products. By the end of WWII several companies followed suit and thus factory finished wood flooring started to become a common product, which also helped the post war military housing boom.