From 2010 through 2015, 13 Mississippi River ports that GAO selected for review varied individually in terms of the amount, type, and trends in traffic handled. As a group, these ports primarily moved a mix of agricultural commodities (corn, soybeans, and rice); petroleum products; and crude materials (such as sand and gravel, among others). However, the ports varied individually, with some primarily moving agricultural commodities, and others moving a variety of commodities. These ports also varied in the quantity of goods transported through them, ranging from less than 1-million tons to more than 10-million tons per year. The amount of freight moved through each port tended to fluctuate each year due to various factors, such as weather, crop yields, and export markets. A majority of the stakeholders GAO interviewed, as well as U.S. Army Corps of Engineers (Corps) officials, stated that funding constraints limit the Corps' ability to fully dredge the 13 ports' harbors, which can affect freight movement. According to local Corps officials, they received about $13.1 million of the $20.6 million needed to fully dredge the 13 ports' harbors in fiscal year 2016. Some stakeholders told GAO that smaller ports are negatively affected by the Corps' emphasis on the amount of cargo moved (measured in tons) when making decisions about which harbors to dredge.