This paper analyses changes in the intensity and duration of US business cycles through the spectrum of turning points chronology. We consider two alternative chronologies: one produced by the NBER dating committees and the other derived from the Markov switching regime model of the growth rate of general economic activity. As a result of favorable changes in economic conditions during the past few decades, the strength of traditional business cycles weakened and spread outside the typical band; that is, the periodicities of 2 to 8 years duration. Modern business cycles appear to be in interaction with major and minor cycles. A major NBER cycle of 10-year duration incorporates, on average, two 5-year cycles and each 5-year cycle embodies two minor cycles. On the other hand, the growth cycle of 10-year duration incorporates, on average, three cycles of 3.5 years duration, and each of them embodies one-and-a-half minor cycles.