This essay tests a dynamic version of the law-of-one-price for U.S. retail markets. The sample consists of retail price differences for a 43-year period over five U.S. cities for various commodity groups. Since relative transportation costs are declining, the law-of-one-price predicts that the...

We explore the hypothesis that income of the rich increases at the expense of income of the poor. In a simple linear regression model, the relative (to the median) incomes of the poor and the rich are significantly and inversely related. Using standard time-series methods, we demonstrate that...