It is important that steel plants are close to markets because their main input, scrap, is widely available. The new steel mills begin to approach the markets and move away from the inputs. At the end of the 20th century, most steel mills in the United States are closed. The survivors are found on the south side of Lake Michigan and on the east coast. Proximity to markets has become more important than the traditional situation factor of proximity to inputs. The growth of manufacturing in the United States was delayed during the nineteenth century, mainly due to the distance of the markets.