In March 2005, the Midwest Independent System Operator (MISO) will begin operating the first ever, formal wholesale market for electricity in the central and upper Midwestern portion of the United States. Region-wide, centralized, security-constrained, bid-based dispatch will replace the current system of decentralized dispatch by individual utilities and control areas. This report focuses on how the operation of generators may change under centralized dispatch. We analyze a stylized example of these changes by comparing a base case dispatch based on a "snapshot" taken from MISO's state estimator for an actual, historical dispatch (4 p.m., July 7, 2003) to a hypothetical, centralized dispatch that seeks to minimize the total system cost of production, using estimated cost data collected by the EIA. Based on these changes in dispatch, we calculate locational marginal prices, which in turn reveals the location of congestion within MISO's footprint, as well as the distribution of congestion revenues. We also consider two sensitivity scenarios that examine 1) the effect of changes in MISO membership (2003 vs. 2004 membership lists), and 2) different load and electrical data, based on a snapshot from a different date and time (1 p.m., Feb. 18, 2004). Although our analysis offers important insights into how the MISO market could operate when it opens, we do not address the question of the total benefits or costs of creating a wholesale market in the Midwest.