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The Anacostia Tributary Trail System (ATTS) is a unified and signed system of stream valley trails joining trails along the Anacostia tributaries of Northwest Branch, Northeast Branch, Indian Creek and Paint Branch with a trail along the Anacostia River, set aside and maintained by the Maryland-National Capital Park and Planning Commission (M-NCPPC) in the Maryland suburbs of Washington, D.C.
ATTS is a part of the East Coast Greenway, a 3,000 mile long system of trails connecting Maine to Florida and the American Discovery Trail, a trail system stretching from the Delaware coast to San Francisco.
The system includes several hiker-biker trails, primarily: the Northeast Branch Trail, the Northwest Branch Trail, and the Paint Branch Trail; all of which are in Prince George's County. The trail system also includes the Sligo Creek Trail, which extends 8.85 miles (14.24 km)  and crosses Prince George's County and Montgomery County. The majority of the routes consist of protected stream valley parks established by M-NCPPC in the 1930s.
The trail system converges on a zero milepost in Hyattsville in an area known as Port Towns, named after the former deepwater port of Bladensburg at the head of the Anacostia River, where the various tributaries converge. A trail along the Anacostia connects the system to Washington, DC near the New York Avenue bridge where it continues as the Anacostia River Trail. And a trail connector from the West Hyattsville Metro Station will eventually connect it with DC's Metropolitan Branch Trail at Fort Totten. The trail system also constitutes part of the Rhode Island Avenue Trolley Trail, with which it connects.
The area covered by the trails corresponds with the coastal plain section of the Anacostia watershed, which consists of wide floodplains that were reserved for parkland and flood-control by the Army Corps of Engineers, using a system of levees and concrete embankments upon which the trails were initially built. In conjunction with the restoration of natural habitat along the adjoining stream valleys in the 1990s, M-NCPPC and Prince George's County Department of Parks and Recreation connected and upgraded the stream valley trails into a consistent network of approximately 24 miles (39 km) of paved 6–10-foot-wide (1.8–3.0 m) off-road paths.
7 miles (11 km) of trail located between Hyattsville and Adelphi near New Hampshire Avenue and the Capital Beltway. The paved trail terminates at the southern terminus of the Rachel Carson Environmental Area just south of the Beltway near Adelphi Mill. The Rachel Carson Greenway extends the Northwest Branch Trail into northern Montgomery County as an unimproved hiking trail, connecting to Wheaton Regional Park.
8.85 miles (14.24 km) of trail located predominately in Montgomery County, ending in Wheaton in the vicinity of Wheaton Regional Park. The Sligo Creek trail originates at the Northwest Branch Trail at Chillum Community Park, Hyattsville, approximately 2.2 miles west of the zero milepost.
The section of trail through Takoma Park was connected to the rest of the Anacostia Tributary Trail System in the late 1990s, as part of a storm sewer reclamation project by the Washington Suburban Sanitary Commission. This section was aligned to follow the path of the storm drain through the narrow valley in the vicinity of the Fall Line.
A connecting trail has been proposed to connect the Anacostia Tributary Trails system to the Metropolitan Branch rail-trail in Washington, to connect several long-distance hiker-biker trails as part of a series of coast-to-coast greenways. The connection would terminate at the Northwest Branch Trail in the vicinity of the West Hyattsville Metro station, approximately 1.8 miles west of the zero milepost, and would parallel the Green Line (Washington Metro) into D.C.
2.5 miles (4 km) of trail located predominately along the levee of the Northeast Branch of the Anacostia River in Riverdale, immediately north of the zero milepost, connecting to Greenbelt Park and the College Park Metro station. The first 1.5 miles of the Northeast Branch from Old Riverdale Road to Calvert Road in Riverdale opened in 1977 and was originally named the Denis Wolf Trail by M-NCPPC. It was named for Wolf, a cyclist killed by a drunk driver in 1974, after Wolf's family raised $3,000 for the trail. Eventually the trail was absorbed into the Northeast Branch Trail, but a Denis Wolf Rest Stop, built in the 1980's still exists just south of Campus Drive.
1 mile (1.8 km) of trail constructed around Lake Artemesia in the vicinity of Greenbelt. The Northeast Branch Trail terminates at the zero milepost of the Paint Branch Trail, where this trail and several other trails split off towards Greenbelt Park.
In 2018, the MNCPPC extended the Little Paint Branch Trail 2.1 miles from it's terminus at the Beltsville Community Center to Cherry Hill Road where it connected to the Paint Branch Trail becoming an extension of the ATTS. 
3.1 miles (1.8 km) of trail located on the edge of Washington along the head of the Anacostia. The trail starts at Colmar Manor, immediately south of the zero milepost and splits in two at the trail bridge over the Anacostia to Bladensburg Waterfront Park in Bladensburg. The west side trail ends at Dueling Creek, short of the Washington line and the east side trail ends at the District boundary just north of the New York Avenue Bridge where it continues as DC's Anacostia River Trail. In 2005, the trail bridge linking Bladensburg and Colmar Manor was completed. In November of 2011, the 1.5 mile section of the west side trail from the waterfront park to an unnamed tributary just north of the District boundary, built in part as environmental mitigation for the new Woodrow Wilson Bridge, was opened. The trail was completed to the boundary in 2016 as part of a stimulus project and opened on Halloween of that year.
A separate system of trails in the upper Paint Branch watershed has been constructed in the Montgomery County portion of Paint Branch Park. The two trail systems are separated by the fall line and the Beltway.