Zitzewitz's suggestion, in a Journal of Industrial Economics March 2003 article, that Britain's pre-World War One lead over the USA in tobacco manufacturing productivity was due to its more competitive market cannot be sustained. A larger country sample shows a positive relationship between concentration and productivity, while accurate measurement of US and UK concentration shows similar concentration levels until 1911. The later US lead, though plausibly induced by antitrust-enforced competition, was due to tougher labour management rather than to stronger technical innovation.