Ms. Rice's address was an appeal to Latin Americans to stay the course with democracy and free trade even though as she admitted, they have not delivered their full benefits to many people in the region.
According to the United Nations, more than 40 percent of Latin Americans still live in poverty, and recent political upheavals have given rise to concerns that the region's democratic trend may be fraying.
In her speech, the secretary of state said she realizes that prosperity "must still seem like a distant horizon" in places like Bolivia and Ecuador, where elected presidents have been turned out of office amid economic discontent.
She said building the institutions of thriving democracies, including reforming markets and curbing corruption, takes time and persistent effort.
"The history of the march of democracy contains a message for every person in this region who feels they have not yet seen its benefit: Do not lose your hope. Do not lose your courage. And most of all, do not turn back now. The answers are to be found in more democratic reform, not less. In time, the blessings to democracy will come to everyone who keeps faith with the principles of democracy,? said Ms. Rice.
Speaking at the Brasilia memorial to Brazil's former President Juscelino Kubitschek, who founded the modernistic capital city 45 years ago, Ms. Rice heaped praise on Brazil as a regional leader and a global partner of the United States.
She said the transformation of Brazil, one of 14 Latin American military dictatorship's in the 1980s, is one of the region's success stories, but that Brazil and others still face the challenge of lifting millions of people out of poverty.
She said this can be achieved through building educational institutions, combating corruption which she called a drag on economies and a "tax on the poor" and opening markets.
Ms. Rice prodded Brazil to press forward on the proposed Free Trade Area of the Americas, for which its leader President Luiz Inacio Lula da Silva has shown little enthusiasm of late.
She said for its part, the United States must ratify its proposed free trade deal with Central America and the Dominican Republic, which is in serious trouble in Congress.
The secretary said the trade deals present a chance to unite 800 million people from Chile to Canada in the world's largest free-trade community, which she said will be "an unstoppable force for prosperity."
Ms. Rice made no direct mention of the Bush administration's rift with Venezuelan President Hugo Chavez, who has been accused by U.S. officials of stifling his political opponents and independent media.
However, in a line of the speech her aides said was directed at Mr. Chavez, Ms. Rice said hemisphere leaders elected democratically "have a responsibility to govern democratically."
Later in a question and answer session with the Brasilia audience, the secretary was more direct, saying threats to democratic institutions in Venezuela should be of regional concern.
"It is not an issue that is just between the United States and Venezuela,? she explained. ?This is an issue of what happens to democratic processes and democratic opportunity in Venezuela. Is there going to be a free press? Will there be the opportunity for opposition to mobilize? How will the congress be treated? What happens to people who are critical of their government? These are the essential values that underscore the great democratic transformation that's taking place in this region."
Brazil's left-of-center government maintains close ties with neighboring Venezuela and Mr. Chavez, and at a joint news conference with Ms. Rice late Tuesday, Brazilian Foreign Minister Celso Amorim appeared to caution the United States against interfering there.
Mr. Amorim said Brazil wanted to be helpful to Venezuela in any way it can, but said problems there have to be worked out by the Venezuelan people, with respect for the country's sovereignty.