CARTAGENA, Colombia — The stereotype of Colombia — violent, chaotic, backward — seemed to be born out in recent days as the army and guerrillas grappled in the countryside and shadowy hit men gunned down a prominent land activist.

But that Colombia seems ever more distant these days. As President Obama arrived Friday in this coastal colonial gem, joining presidents and corporate chief executives at the Summit of the Americas, he heard about another Colombia: prosperous, a magnet for investment, ever more urban and modern.

It is the Colombia that attracted record levels of foreign investment and whose economy grew nearly 6 percent last year, that was awarded investment-grade status and can borrow more cheaply than some countries in Western Europe.

It is also a country that is finally starting to mirror neighbors such as Brazil by undergoing an expansion of the middle class that could make it an important consumer market. Colombia is the third-most populous country in Latin America, with 46 million people.

Finance Minister Juan Carlos Echeverry, who recalled how he was constantly peppered with questions about drug trafficking when he studied in New York in the 1990s, said he now tries to lure foreign investors with talk about “the Colombian miracle.”

The economic and demographic trend lines, he said, show that Colombia in a few years will surpass Argentina to become South America’s second-largest economy.

“People want to come to Colombia,” said Echeverry, who was a teaching assistant to Ben S. Bernanke, the U.S. Federal Reserve chairman, when he was working on his doctorate in economics at New York University in the 1990s. “There has been this humongous, tectonic change of stereotype of Colombia, to promised land from wasteland.”

Most Colombians do not see it as a stereotype: In the 1980s and early ’90s, cocaine kingpin Pablo Escobar and his henchmen assassinated policemen and high government officials and even detonated a bomb on an airliner. A dozen years ago, some policymakers worried that a potent rebel group could take power, wealthy and educated Colombians fled the country and the economy struggled.

The changes since are readily seen in revamped airports, construction sites in big cities and billion-dollar business deals by Colombian companies that trade on the New York Stock Exchange. Following trends set by Brazil and Chile, Colombian companies are expanding abroad.

Last year, for instance, Suramericana, a Bogota-based conglomerate, beat out insurance heavyweights such as Metropolitan Life and Prudential to take control of ING’s operations in several Latin American countries, a deal worth $3.7 billion. Nutresa, a food conglomerate, has gained an important foothold in the Caribbean and now has 30,000 workers. And with new acquisitions in Mexico and Chile, the venerable paper and printing company Carvajal has become the second-biggest company of its kind in Latin America.

“Colombia has started to become a protagonist in Latin America,” said Suramericana’s chief executive, David Bojanini. “Those are companies that have operated at a high level for some years but have recently focused on becoming world class to compete in a globalized world.”