In June, we presented national data from one of the first attempts to measure the size of provider networks in plans sold on the health insurance marketplaces. We used simple “T-shirt” sizes to categorize networks in a way that could help consumers quickly grasp the choices they were making. In this Data Brief, we present network sizes summarized up to the level of the state and the rating area. This analysis should help regulators and consumers assess and understand the trade-off between premiums and network size as we enter the next open enrollment period.