At the stroke of midnight, a planeload of flowers – an important export for Colombia – left Bogota to become the first shipment under the deal. Later on Tuesday, a Harley-Davidson motorcycle was set to be unveiled as one the first U.S. exports to Colombia as part of the agreement.

Both countries hope the deal will boost mutual exports and investments, as well as underpin the two countries’ close political ties. Colombia has long been seen as one of the United States’ staunchest allies in the region.

The pact means a wide variety of goods, including machinery, raw materials and agricultural products, can be traded without import tariffs needing to be paid. The US International Trade Commission estimates that the value of US exports to Colombia could rise by more than $1 billion, while Colombian exports the other way could grow by $487 million.

The accord, signed during President George W Bush’s administration, was opposed by U.S. labour groups, who feared job losses. Many Democratic members of Congress argued that it should not be approved until they were satisfied Colombia had done enough to stop violence against union organizers. There was also opposition from Colombian trade unions, who expressed concern about whether the country was developed enough to compete.