Earlier work on U.S. import demand suggest that structural change may have occurred sometime in the mid-1960s. Since this evidence was based upon a somewhat arbitrary splitting of the sample period, the dating of change is uncertain. In this paper we investigate the question of structural change for both U.S. imports and exports, using a procedure that lets the data determine if and when structural change may have occurred. We find weak evidence of structural change for imports in the mid- to late 1960s and much stronger evidence in 1972:1 and thereafter. There is no evidence of structural change for exports.

Earlier work on U.S. import demand suggest that structural change may have occurred sometime in the mid-1960s. Since this evidence was based upon a somewhat arbitrary splitting of the sample period, the dating of change is uncertain. In this paper we investigate the question of structural change for both U.S. imports and exports, using a procedure that lets the data determine if and when structural change may have occurred. We find weak evidence of structural change for imports in the mid- to late 1960s and much stronger evidence in 1972:1 and thereafter. There is no evidence of structural change for exports.