The dedication was initiated by an act of Congress.[2] President Joe Biden signed H.R. 2278, officially designating the trail route on October 13, 2021.
The triangular-shaped trail - to the sites of the memorials in Arlington, Virginia and New York City, and near Shanksville, Pennsylvania - passes through six Mid-Atlantic states and Washington, D.C.[3] At its inception it incorporated 55% off-road trails and 45% existing roadways.[4] A 1.5 mile purpose built section was added thereafter.
Clockwise from the Pentagon the triangular 9/11 Trail incorporates many sections of existing trais, as well as overlapping segments of the East Coast Greenway.