A multi-part test is proposed for the hypothesis that American production agriculture is shrinking. The results of the three tests presented here are consistent with a shrinking American agricultural sector that is on the verge of, but not yet in, the final decline stage of its "life cycle." The sector is clearly shrinking in relative size and importance, and in absolute size, and its economic performance has been weak for decades. These changes in agriculture and their implications for the agricultural economics profession are discussed. Finally, (at least) two challenges to American agriculture and the agricultural economics profession are raised.