As President Trump continues to place import tariffs on items ranging from aluminium to solar panels, people are arguing over their effectiveness. 

But they are nothing new.  In 1994 the US placed them on Chinese pencil imports that it said were being sold at under cost price.  One of the few remaining US pencil-makers, Musgrave Pencils of Shelbyville, Tennessee, says they kept the industry from being completely lost. 

Video journalist: Zoe Thomas