The United States' economic slump has contributed to the changing dynamic. But so has a wave of broad-based economic growth in Latin America that has lifted some 50 million people into the middle class since 2003, allowed countries such as Brazil to pay off debts to the IMF, and made the region broadly less subject to foreign pressure.

Although there are exceptions, Latin America as a whole has also become more democratic. That makes it more complicated for Washington to shape events than it was during the 20th century...

However, new trade talks have faced huge barriers in recent years because of strains on the global economy and Latin American countries are likely to be even more insistent on negotiating thorny issues like U.S. agricultural subsidies than they were in the past.

That's in part because they have other options. China's trade with Latin America soared from near nothing in the past decade and now accounts for about 11 percent of trade in the region. The U.S. share has fallen from 53 percent to 39 percent.