The U.S. Geological Survey (USGS) works closely with the Mississippi Department of Transportation (MDOT) to provide information to be used by the MDOT for design of highway-drainage structures. MDOT spends millions of dollars annually for highway construction. Streamflow records, hydrologic analyses of basins, and hydraulic analyses of flooding potential at proposed highway crossings help the MDOT to make more informed decisions on the use of highway construction funding. Flood-frequency and hydraulic characteristics at highway crossings are determined from historical flood-elevation data recovered by the USGS, cross-section data, and correlations with data from nearby gaging stations. Additional streamflow data are collected for ungaged [...]