The naval proving grounds near Washington, D.C., at Indian Head, Maryland, was suffering from encroachment of local development around the time of World War I and so the U.S. Navy established a "Lower Site" downriver on the Virginia side of the Potomac River between Mathias Point and Upper Machodoc Creek. Shortly after its establishment the naval base and surrounding area were both named in honor of the Civil War era admiral John Dahlgren, known as the father of naval ordnance. This area was very rural and gave the navy plenty of room for its activities, but the remoteness and lack of development of the area also made it difficult to move men and material back and forth. During the run up to World War II this problem became critical and so the U.S. government began construction of the Dahlgren Railroad, a branch line from the Richmond, Fredericksburg and Potomac line near Fredericksburg to the naval proving grounds at Dahlgren. Land was acquired in 1938, construction began in 1941 and operations commenced in 1942.

In the 1960s, no longer making use of the railroad, the U.S. government sold the road to the RF&P which began operating it for the benefit of industrial and other commercial interests established along the branch line. Today, CSX which acquired the RF&P operates the line with its only significant traffic being coal delivered to a power plant and refuse delivered to a landfill, both in Sealston. Since the the portion of the line east of Sealston was no longer in use, CSX offered to sell that portion, and it was purchased by a local resident who has worked to open the trail as a public greenway.

Because of some local opposition, the trail is not yet freely open to the public and explicit permission is needed to use the trail. Fortunately, Dave Jones, president of the Friends of the Dahlgren Railroad Heritage Trail has graciously invited all geocachers to search the trail as his guest; he only asks that you be sure to let others, especially local and state government officials, know about how enjoyable the trail is and what an asset to the area it would be for it to become a public trail.

There are just a few trailheads along this 16 mile trail; the one most convenient for finding the cache is on Indiantown Road. It is a hike of about 2.8 miles from there eastward to where the trail passes under Caledon Road and where you will find the cache. Please, don't try to access the cache directly from Caledon Road since there is no legal parking there and the trail embankment is dangerously high and steep.  Trust us, the exercise will do you good and this is a beautiful trail through wetlands teeming with interesting flora and fauna.