This paper has two main objectives. First, to provide empirical support to the traditional assertive that Brazil still constituted an ''archipelago'' of economic islands until at least the end of the 40's. Second, to describe the commercial relationships among the Brazilian states and regions in the decades which immediately preceded and succeeded the face of acceleration in the process of market integration in the country. The paper shows, by making use of four interstate trade matrices, that only after the completion of a national program of roadways construction, in the 50's and 60's, Brazil effectively broke up the state of relative isolation of its regional economies. The impressive expansion of the internal trade flows, starting in the 50's, attests to the striking intensification of the integration process and the formation of a virtually unified national market.
