Heartland's sister company in Canada buys sugar at international prices, and conjures up a molasses stew specifically designed to avoid America's customs tariffs.

ECONOMIST: Sugar solution

Harmonising customs and tariffs between the two has been tricky.

ECONOMIST: Montenegro

The agreement is designed to boost trade between the two blocs by removing various tariffs and customs barriers.

BBC: MEPs back Latin American trade agreement

NAFTA's complex rules of origin, moving instead towards a customs union with common tariffs on goods from other countries (to be set at the lowest level of any of the three).

ECONOMIST: North America

With simplified customs and exemptions from certain tariffs we'll encourage more businesses to engage in more trade.

WHITEHOUSE: President Obama Holds a Press Conference at the APEC Summit

The new restrictions range from higher tariffs to costly import licences and customs controls.

ECONOMIST: Trade

On the import side, Argentina cannot raise tariffs on its own because it belongs to the Mercosur customs union.

ECONOMIST: Protectionism in Argentina

The customs union might survive, and develop further, if Brazil were to accept its partners' desire for lower external tariffs all round, especially on capital goods.

ECONOMIST: Another blow to Mercosur