Fernández, especially, distanced Argentina from the United States. She clashed with American companies; unleashed fiery anti-U.S. rhetoric; and pitted her government against New York hedge funds in a high-profile debt dispute. That, together with protectionist economic policies like trade restrictions and currency controls, dissuaded foreign investors.

But now, with the administration of President Mauricio Macri making swift market-oriented reforms--including settling with hedge funds that held defaulted Argentine sovereign bonds--and Obama offering renewed bilateral cooperation, their interest is piquing.

"It's a historic opportunity to relaunch the relationship between the United States and Argentina," says Daniela Martin, managing director of AmCham Argentina, the American Chamber of Commerce in Argentina. "Obama's visit will work like a catalyst. It will put Argentina back in the shop window."