The Streamer map shows all of the rivers of the United States and allows you to zoom in and out on a specific river and to trace the course of the river either upstream or downstream. This program is located on the National Atlas website http//nationalatlas.gov/streamer/Streamer/streamer.html.
The map below is an upstream trace of the Mississippi River, which shows all of the rivers and streams that make up the watershed of the Mississippi River.
The map below is a downstream trace of the Red River from it's beginning as Little Red River just East of Silverton, Texas to where it empties into the Atchafalaya River and then into the Gulf of Mexico.
You may ask, "Why is this type of map important to genealogists?" As genealogy researchers we need to remember that our ancestors did not have the means of travel that we enjoy today. One of the major means of transportation in the United States and Colonial America before trains, automobiles and airplanes was the rivers. How did your ancestors travel to the places they resided?
One of my roadblocks in my research has been to determine the route my fourth great grandfather, Hugh Jones, took from Orange County, Virginia to Anson County, North Carolina where he met and married my fourth great grandmother Lydia White Jones. My assumption for many years had been that he left home at a young age and traveled the "Fall Line" Road to an area on the border of North and South Carolina near Anson County. Several of his older brothers and sisters move to a location in North Carolina called "Happy Valley" on the banks of the Yadkin River near Lenoir and Wilkesboro, NC following the Revolutionary War. The road that they used was probably the "Upper Road"which was West of the "Fall Line" road. After seeing the route of the Yadkin and Pee Dee rivers on this map, I wonder, did Hugh come to the northern part of North Carolina with his brothers and sisters and then decide to move on South to greener pastures? This map shows that it would not have been difficult to make this move and this idea has opened up new research possibilities for me to use to break through this brick wall.
I love using maps to do my genealogy research and this is one of the greatest map tools that I have seen.
Happy ancestor hunting.