In 1985, the Blackstone River Valley National Heritage Corridor was designated by the United States Congress, following the path of the Blackstone River from Providence to Worcester. ;Rhode Island In 1997, the Rhode Island Department of Environmental Management and Department of Transportation began work on the first Rhode Island segment, from Lincoln to Ashton. This segment was completed in 1998. A second Rhode Island segment was completed in 2002, from Ashton to Manville. In August 2007, a bridge reconstruction project at Martin Street in Lincoln was completed, ending a three-year bike path closure. The new bridge incorporated a major safety improvement with the path passing underneath Martin Street instead of meeting it at grade. In November 2007, a extension from Manville to the Woonsocket Water Treatment Plant was opened. A segment from Lonsdale to Valley Falls, which includes more than of boardwalk over part of the Lonsdale Marsh, opened in 2008. A segment through the River's Edge Recreational Complex in Woonsocket was completed in 2008, and that segment was linked to the previously-completed portions to the south later that year. In 2011, an segment of on-road bicycle lanes opened connecting the Blackstone River Greenway with the East Bay Bike Path, starting in Providence. In 2013, sharrows were painted through Woonsocket from the Massachusetts border to the River's Edge Recreational Complex. In early Summer 2017, a new section of path was completed in Providence, stretching from Gano Street to Pitman Street, along the Seekonk River. As of 2017 the bike path is long, of which make up the longest segment, and additional segments are under design to extend the path further through Woonsocket toward the Massachusetts border and through the cities of Providence, Pawtucket, and Central Falls. Construction of Section 8C from Cold Spring Park to the Massachusetts border was awarded to John Rocchio Corporation with a $2.8 million bid and a July 19, 2019 substantial completion date. ;Massachusetts In 1996, a study undertaken by the Massachusetts Highway Department and the Massachusetts Department of Conservation and Recreation produced a plan for seven segments of trail linking Worcester with Blackstone, Massachusetts and the Rhode Island border.
Construction was delayed due to a lack of state funds, a shortfall attributed to the over-budget "Big Dig" highway tunnel project in Boston. In 2005, as part of the Massachusetts Turnpike-Route 146 interchange project, the first segment, from Worcester to Millbury, was opened to the public. In 2010, an agreement was reached between MassDOT and DCR for DCR to take over the management of the design and environmental permitting of Sections 1 through 5 of the Greenway, including preparation of the Environmental Impact Report. Section 6 was previously constructed by MassDOT, and Section 7 will be designed by the City of Worcester, and constructed by MassDOT. In 2013, five bridges in Blackstone that run concurrently with the Southern New England Trunkline Trail were repaired and repainted. These are the two Factory Pond Bridges, the northern Canal Street Bridge, a Blackstone River Bridge, and the St. Paul Street Bridge. By September 2014, these bridges received new ipe wood decks and safety railings. In 2014, new bridges were also constructed over Kane Court and Main Street, and a tunnel was built under Church Street, all in the town of Blackstone. The entire 3.7-mile path was finally completed in December 2016. All of the trail between the missing Blackstone River and Rte. 122 bridge in Blackstone and Rte. 146A in Uxbridge is part of both the SNETT and the Blackstone River Greenway.
