The Failure of the U.S. trade deficit to show marked improvement after two years of a falling dollar has become a major source of strain in the politics of economic policy. Frustrated with the persistence of the trade deficit, the administration has demanded reflation by unwilling German and Japanese governments. Congressional calls for protectionist measures have become increasingly strident. Also at stake is the credibility of mainstream economists. Since signs of a deterioration in U.S. trade performance became clearcut in 1982, most economists have argued that the fault lay in the strong dollar, not in other popular villains such as foreign countries' industrial policies. Further, the role of the dollar in causing the trade deficit is a key part of the widely accepted doctrine that links trade deficits to the federal budget deficit. if the trade deficit remains intractable, this doctrine, which has served as a potent defense against nationalistic views of the trade problem, will soon lose its effectiveness. The purpose of this paper is to analyze the puzzling persistence of the trade deficit. We consider and reject several ideas that have recently become popular in explaining that persistence, and conclude that a valid explanation has three main parts. First is the accepted view that there are substantial lags in the adjustment of both prices and quantities to exchange rates, probably representing a tendency of firms to commit themselves to suppliers for extended periods of time. The effect of these lags has been heightened by the timing of the dollar's rise and fall: because the dollar rose steeply before it began falling, firms were still adjusting to the strength of the dollar and shifting to foreign suppliers even as the dollar fell. Second, the failure of foreign demand to grow as rapidly as U.S. demand since 1980 means that, other things equal, the dollar would have to fall below its 1980 level to restore the 1980 trade position. Finally, the evidence suggests that even if both the real exchange rate and relative demand were restored to their 1980 levels, the trade balance would still not return to its original position. At least in the years before 1980, there appears to have been a secular decline in the U.S. real exchange rate consistent with any given trade balance, but we have been unable to extract clear evidence of such a continuing trend from the data. The paper is in six parts. The first part reviews some basic facts about U.S. trade performance, especially since the turnaround of the dollar in the first quarter of 1985. The second part addresses three widely circulated views about the reasons for a persistent trade deficit that can be confronted and rejected without formal econometric testing. The third part presents some "conventional econometrics" on U.S. trade, estimating a simple model of the nonagricultural, nonoil trade balance. The fourth part consider the issue of lags, presenting and testing some alternative views about the reasons for long lags in both prices and quantities. The fifth part addresses the possibility of a downward trend in the equilibrium exchange rate and asks whether the strong dollar itself shifted down the equilibrium exchange rate. The last part of the paper pulls the results together for an overall assessment. [ABSTRACT FROM AUTHOR]