In 1972, Berwick Forge & Fabricating, of Berwick, Pennsylvania began producing modern 50? sliding door box cars which featured their new corrugated non-terminating ?sine-wave? ends. Initially sold to over 35 railroads across the nation, these box cars were an unfortunate casualty of the economic recession of the late 1970?s and Berwick was forced to stop production in 1982. However, Berwick?s 50? hauler found a place in railroad history through a strong second hand market that continues even today.