The Long-Wave theories of Nikolai Kondratiev and others claim to find mathematic waves in economic and other social data which are at present in dispute. Currently the theory is considered outside the scope of mainstream economics under several rationales.

Despite the lack of mainstream acceptance, we make a strong case for the existence of long waves in the Real GNP of the United States with a 56 year cycle. Our analysis bypasses many of the issues cited by Long-Wave theory critics and in fact clarifies the mathematical structure of the theory.