As trade barriers have been lowered over the decades, much has changed, evidenced by the emergence of critical mass in many export markets, the growing importance of multinational firms, and the rise of production processes that are integrated across borders.
*** The interaction of a wide range of economic forces, which adjust at national borders to create what we call the current account balance, has proved difficult to predict with any precision, primarily because of the difficulty of forecasting exchange rates. These same forces have lessened our ability to anticipate the consequences of a buildup of either a surplus or a deficit.