A coherent plume from the Mississippi River was detected in MODIS imagery in July--October 2004 extending from the eastern Gulf of Mexico into the Florida Straits (FS), and reaching the Gulf Stream (GS) off Georgia. The plume was sampled from ships in the FS and the GS. In early August, the plume was about 10--20 km wide in the western FS and about 50 km wide off Georgia. The FS ship survey (16--26 August) documented a 50 km, 10--20 m deep band with anomalies in surface salinity (-0.8), temperature (0.5¿C), and surface chlorophyll concentration (2¿) relative to FS waters outside the plume. Nutrient concentrations were only slightly higher in the FS plume and there was no apparent increase in colored dissolved organic matter. We estimate that the plume carried some 23% (~2778 m3 s-1) of the Mississippi River discharge between July and September 2004 into the GS.