This paper discusses American long-term experience with changes in the distribution of income since the turn of the century. It supplies quantitative documentation of a pronunced secular swing in inequality. Inequality indicators were on the rise up to 1914, exhibited no trend to 1926 or 1929, and traced out a well known egalitatian leveling up to 1948. The paper uses a simple general equilibrium model to decompose the sources of these macro distributional trends. This approach supplies a concrete means by which to isolate the main causes of movements in the wage structure, factor shares, numbers in poverty, and size distribution statistics. Hypotheses regarding macro distribution performance over time can be readily classified as related to factor demand or factor supply. These two forces need not be in conflict, however. Contrary to conventional wisdom, the key forces appear to have come from the factor demand side rather than from the supply side. That is, the combined effects of demographic, immigration, and capital (human and non-human) formation forces are found to have been small when compared with factor demand. The latter includes sectoral imbalances in rates of technological change, exogenous changes in demand mix, and, less important, factor-saving biases in new technologies. (Author/JM)