From the 20 June 2010 Financial Times: "The US remained the worlds biggest manufacturing nation by output last year, but is poised to relinquish this slot in 2011 to China thus ending a 110-year run as the number one country in factory production". If we talk in terms of PPP (and discount the pegging of the yuan to the dollar) China would have surpassed us a bit sooner I think.
Prior to 1900, the UK was the largest manufacturer in the world.
Prior to 1900, the UK was the largest manufacturer in the world.