This report reviews reports of congestion costs and begins to assess their implications for the current national discussion on the importance of the U.S. electricity transmission system for enabling competitive wholesale electricity markets. We draw the following conclusions: 1) Information about the operation of congestion revenue rights markets is needed to assess the impacts of congestion revenue charges on consumers; 2) Information on generators' offers is needed to assess system redispatch payments; 3) Many studies presume that generator offers reflect competitive market conditions; 4) Customer costs may rise as a result of reducing congestion; 5) Minimizing consumer costs may not increase aggregate social wealth; and 6) There is no standardized conceptual framework for studies of congestion costs.