The Rapidan River, flowing 88 miles (142 km) through north-central Virginia in the United States, is the largest tributary of the Rappahannock River. The two rivers converge just west of the city of Fredericksburg. The Rapidan River begins west of Doubletop Mountain in Shenandoah National Park where the Mill Prong meets the Laurel Prong at Rapidan Camp, approximately 3 miles (4.8 km) south of Big Meadows.
Sections of the lower Rapidan River are preserved by a conservation easement.
The Rapidan River was the scene of severe fighting in the American Civil War, and historic sites such as Ely's Ford, Chancellorsville, Brandy Station, Kelly's Ford, and the Battle of the Wilderness are nearby.
The Rapidan River ranks #38 in Trout Unlimited's Guide to America's 100 Best Trout Streams. In 2000, the upper Rapidan River was nominated for EPA designation as a Tier III Exceptional Waterway. In 2001, the Virginia Department of Environmental Quality rejected the application, due to a nearly-complete lack of information about the impact of the designation, and the corresponding objection of every affected riparian landowner.
- Mill Prong Trail to Rapidan, 3.6 miles (5.8 km) - Enjoyable hike to Rapidan Camp. The trail starts high in the Blue Ridge Mountains (3,200 ft) on Skyline Drive, goes southeast 1.8 miles (2.9 km) to the headwaters of the Rapidan River and returns to the point of origin. Note: This trail will not take you to the Rapidan Canal of the Rappahannock Navigation.
- Shenandoah National Park - Rapidan Loop, 7.4 miles (11.9 km) - The trail starts high in the Blue Ridge Mountains (3,200 ft) on Skyline Drive and loops, following the Mill Prong and Laurel Prong and includes the confluence of the two prongs. The Rapidan River is formed at the confluence. Note: This trail will not take you to the Rapidan Canal of the Rappahannock Navigation.
- U.S. Geological Survey. National Hydrography Dataset high-resolution flowline data. The National Map, accessed April 1, 2011
- "City of Fredericksburg Finalizes 4,232-acre Conservation Easement Agreement with The Nature Conservancy, Virginia Outdoors Foundation and Department of Game and Inland Fisheries". The Nature Conservancy. 2007-03-14.
- Ross, John (2005). Trout Unlimited's Guide to America's 100 Best Trout Streams. Guilford, Connecticut: Globe Pequot. pp. 135–138. ISBN 1-59228-585-6. Retrieved 2010-08-11.
- Jones, Tom. "Rapidan River Tier III". Rapidan Camps. Retrieved 2008-06-19.