MEXICO CITY  Mexico’s former president, Carlos Salinas, used to promise that free trade and foreign investment would jump-start this country’s development, empowering a richer and more prosperous Mexico “to export goods, not people.”

Fifteen years after the North American Free Trade Agreement took effect, only the first part of that promise has been realized.

Mexico’s exports have exploded under Nafta, quintupling to $292 billion last year, but Mexico is still exporting people too, almost half a million each year, seeking opportunities in the United States that they do not have at home.

Secretary of State Hillary Rodham Clinton will arrive in Mexico on Wednesday and President Obama will visit next month. Both are expected to emphasize the successes of American-Mexican economic cooperation, but it will be hard to ignore how much in Mexico has not changed under Nafta.