<P> In August 1955, severe flooding on the Blackstone caused extensive damage to Woonsocket, Rhode Island . Where the river is usually 70 feet (21 m) wide it swelled to over 1 mile (1.6 km) wide . The flooding of the Blackstone was the result of a succession of dam breaks and was caused by rainfall from Hurricane Connie followed a week later by Hurricane Diane, which together deposited over 20 inches (510 mm) of rain in parts of Rhode Island and Massachusetts . The Blackstone river reached a stage of 21.8 feet (6.6 m) in Woonsocket, which remains the flood of record; flood stage is 9.0 feet (2.7 m). </P> <P> The river, together with the Woonasquatucket River to the south, was designated an American Heritage River in 1998 . </P> <P> The river is formed in Worcester, Massachusetts by the confluence of the Middle River and Mill Brook . From there, it follows a rough southeast course through Millbury, Sutton, Grafton, Northbridge, Uxbridge, Millville, and Blackstone . It then continues into Rhode Island, where it flows through Woonsocket, Cumberland, Lincoln, Central Falls, and Pawtucket, where the river then reaches Pawtucket Falls . After that, the river becomes tidal, and flows into the Seekonk River just north of Providence . Other tributaries join the Blackstone along the way, such as the West and Mumford River, at Uxbridge, and The Branch River in North Smithfield . </P> <P> The Blackstone River has a long association with industry, and a legacy of pollution as a result . By 1900 the river was already considered polluted and the Massachusetts Department of Public Health said in a report, "The Department finds that the condition of the Blackstone River is offensive throughout its course, from Worcester to the state line at Blackstone . The condition of the stream is likely to grow worse until effective measures are completed for removing from the river much of the pollution which it now receives ." Little was actually done to abate this pollution for the next 72 years, until the passage of the Clean Water Act began to spur some action on the part of States and the Federal Government to clean up polluted rivers and streams . Progress was slow, and as recently as 1990, the United States Environmental Protection Agency called the Blackstone, "The most polluted river in the country with respect to toxic sediments ." </P>

Where does the blackstone river start and end
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