The Bush administration has signed a multi-billion dollar free trade agreement with Colombia.
The trade deal was signed after two year's of negotiations
The pact comes despite warnings from Congress - which is now controlled by the opposition Democratic Party - that it has deep reservations over the deal.
Colombia's finance minister said the move would benefit Colombia's economy and its efforts to improve security.
The deal is America's biggest in the Western Hemisphere since 1994's North American Free Trade Agreement (Nafta).
However, the deal has yet to win Congressional approval.
Agreements with Peru and Vietnam are awaiting similar approval, while US trade officials are trying to negotiate trade deals with countries including Malaysia and South Korea.
Pressure for the agreements to be approved is mounting, as US President George W Bush's special "fast-track" authority to negotiate trade deals expires next year.
After 30 June 2007, the US Congress will once more have the right to change or veto any agreement that Mr Bush signs.
Congress has voiced objections to the trade pact with Colombia as it fails to protect internationally agreed worker rights such as the abolition of child labour, protection against discrimination and freedom to join a union.
Opponents of the Bush administration also claim that such deals do little to protect US companies from unfair trade practices.
"The agreement will deepen and strengthen our trade ties by providing new opportunities for US businesses, manufacturers, farmers and ranchers to export their goods and services to one of Latin America's most robust economies," deputy trade representative John Veroneau said.
Once agreed, it is expected to make more than 80% of US consumer and industrial exports to Colombia duty free. Trade between the two countries reached $14.3bn ($11bn) last year.
"The Free Trade Agreement will create permanent commercial channels so that our products could compete in the US market, therefore creating more revenue and jobs for millions of Colombians," Colombia's finance minister Jorge Humberto Botero added.
Mr Botero also said the pact would "be a great tool" in the US-backed fight against terrorism and drug-trafficking