Answer:
The sugar industry in the US is very powerful and has been able to establish trade barriers and import quotas that affect domestic prices. Sugar prices in the US are extremely high compared to prices in any other country, including Canada, Mexico, China, European nation, i.e. American sugar is the most expensive in the world.
Besides imposing trade barriers, the government also imposes a binding price floor. Binding price floors always result in deadweight losses since the quantity demanded is lower than equilibrium. This is why American candy manufacturers move their production overseas. the highest cost in the candy industry is actually sugar, and wherever they decide to relocate their factories it will always be cheaper.