Empirical evidence suggests that the differences in rates of technical progress across sectors are time-variant, implying that the bias in technological change is not constant. In this paper, we analyze the implications of this nonconstant sectoral biased technical change for structural change and we assess whether this is an important factor behind structural transformations. To this end, we develop a multi-sectoral growth model where TFP growth rates across sectors are non-constant. We calibrate our model to match the development of the U.S. economy during the twentieth century. Our findings show that, by assuming nonconstant biased technical change, a purely technological approach is able to replicate the sectoral transformations in the U.S. economy not only after but also prior to the World War II.