European economic integration is commonly believed to be incomplete, and that further reforms are needed. In this context, the union of U.S. states is considered the benchmark of complete economic integration and is often the basis for comparison regarding the extent of E.U economic integration....

We first demonstrate that, within a fully integrated economy (FIE) in which there is free mobility of goods and factors, each FIE member's share of total FIE output will equal its shares of the total FIE stock of each productive factor. This equal-share property implies that, if economic...

We show that in a fully integrated economy, in which there is free mobility of goods and factors, each member’s share of total output will equal its shares of total stocks of productive factors (i.e., physical and human capital). We label this result the equal-share relationship. This...