In remarks to a CEO summit, Mr. Obama spoke of impressive economic growth in Latin America, progress moving tens of millions of people out of poverty, and a growing middle class.
He pointed to two U.S. free trade agreements, with host country Colombia and with Panama, and said some 40 percent of U.S. exports go to the region, supporting almost four million U.S. jobs.
But Mr. Obama said barriers remain to greater entrepreneurship and innovation, and that trade across a hemisphere with nearly one billion citizens is only half of what it could be.
Mr. Obama said "stark inequalities" endure in the region, with "far too many" people still living in poverty, adding the challenge will be to ensure broad-based prosperity. "The challenge for this hemisphere is how do we make sure that globalization and that integration is benefiting a broad base of people," he said.
In a first for the Summit of the Americas, Mr. Obama, Brazil's president, Dilma Rousseff, and the summit host, Colombian President Juan Manuel Santos, engaged in a panel discussion.
President Rousseff repeated concerns about the impact on developing nations of "expansionary monetary policies" and warned against protectionism. The Colombian leader said he shared concerns about monetary policy.
President Obama said he is sympathetic to the challenges around monetary policy in developed and less developed countries. The president, however, said the issue involves not just the United States but "the failure of some other countries to engage in re-balancing."
Mr. Obama also said economic success in the hemisphere depends in the long-term on democratic governance. "When we look at how we are going to integrate further and take advantage of increased opportunity in the future, it is very important for us not to ignore how important it is to have a clean, transparent, open government that is working on behalf of its people," he said.
President Obama called the Free Trade Agreement with Colombia a "win-win" for both countries, saying it contains strong labor and environment provisions.
On the controversial issue for many countries of drug policy reform, Mr. Obama reiterated his opposition to legalization of drugs, though he recognized the "brutal" toll drug violence and said he is open to "legitimate discussions."
In translated remarks, President Santos said Colombia had been "relatively successful" in the war on drugs, but spoke of the need to consider alternatives. "Right now, we are in a moment of analyzing if what we are doing is the best that we can do or if we can maybe find an alternative that is much more effective and less expensive for the societies in general," he said.
After a colorful formal opening ceremony, the 33 hemisphere leaders began a multi-hour main plenary session discussing not only economic integration, but steps to eliminate poverty and inequality, transnational crime and access to technology.
A Venezuelan Foreign Ministry official announced that President Hugo Chavez, a harsh critic of U.S. policies, will not attend the Cartagena summit.
Mr. Chavez was to return to Cuba to receive additional radiation treatment for the cancer he has been battling.