The paper analyzes from the references if the firms are concentrated geographically outperform their counterparts more dispersed. In this regard, it was found that it is possible to belong to a cluster may have positive externalities due to the proximity of businesses; however there may be economies of congestion and heterogeneous benefits that offset these advantages. The definition of negative or positive externalities for clusters and their companies depend on the context in which they are located, so it should be avoided generalizing concepts from research findings that could divert important decisions.