Question: The West Branch of the Dead Diamond River is a tributary located in a river that is how long?
Context: The West Branch of the Little Dead Diamond River is a 2.5 mi long river in northern New Hampshire in the United States.  It is a tributary of the Little Dead Diamond River, located in the Androscoggin River watershed of Maine and New Hampshire. The West Branch of the Dead Diamond River is a 2.7 mi long river in northern New Hampshire in the United States.  It is a tributary of the Dead Diamond River, located in the Androscoggin River watershed of Maine and New Hampshire. The West Branch Susquehanna River is one of the two principal branches, along with the North Branch, of the Susquehanna River in the northeastern United States.  The North Branch, which rises in upstate New York, is generally regarded as the extension of the main branch, with the shorter West Branch being its principal tributary.  The West Branch, which is 243 mi long, is entirely within the state of Pennsylvania, draining a large mountainous area within the Allegheny Plateau in the western part of the state.  Along most of its course it meanders along mountain ridges and through water gaps, forming a large zigzag arc through central Pennsylvania around the north end of the Allegheny Ridge.  In colonial times the river provided an important water route to the Ohio River valley.  In the 18th century, its lower valley became a significant industrial heartland of Pennsylvania.  In the 20th century the upper reaches of the West Branch turned a yellow/orange color due to sulfurous drainage from nearby and abandoned deep bituminous coal mines. The South Branch of the Little Dead Diamond River is a 4.3 mi long river in northern New Hampshire in the United States.  It is a tributary of the Little Dead Diamond River, located in the Androscoggin River watershed of Maine and New Hampshire. The Androscoggin River is a river in the U.S. states of Maine and New Hampshire, in northern New England.  It is 178 mi long and joins the Kennebec River at Merrymeeting Bay in Maine before its water empties into the Gulf of Maine on the Atlantic Ocean.  Its drainage basin is 3530 sqmi in area.  The name "Androscoggin" comes from the Eastern Abenaki term "/aləssíkɑntəkw/" or "/alsíkɑntəkw/", meaning "river of cliff rock shelters" (literally "thus-deep-dwelling-river"); or perhaps from Penobscot "/aləsstkɑtəkʷ/", meaning "river of rock shelters".  The Anglicization of the Abenaki term is likely an analogical contamination with the colonial governor Edmund Andros. The East Branch of the Dead Diamond River is a 12.7 mi long (20.4 km) river in northern New Hampshire in the United States.  It is a tributary of the Dead Diamond River, located in the Androscoggin River watershed of Maine and New Hampshire. The Middle Branch of the Dead Diamond River is a 9.0 mi long river in northern New Hampshire in the United States.  It is a tributary of the East Branch of the Dead Diamond River, located in the Androscoggin River watershed of Maine and New Hampshire. The Little Dead Diamond River is a 7.1 mi long river in northern New Hampshire in the United States.  It is a tributary of the Dead Diamond River, located in the Androscoggin River watershed of Maine and New Hampshire. The Swift Diamond River is a 17.8 mi river in northern New Hampshire in the United States.  It is a tributary of the Dead Diamond River, located in the Androscoggin River watershed of Maine and New Hampshire. The Lackawanna River is a 40 mi long river flowing into the Susquehanna River with 65 named tributaries, of which 33 are direct tributaries.  The river flows through Susquehanna, Lackawanna, and Luzerne Counties in Pennsylvania.  The shortest tributary is 0.4 mi long, while the longest is 21 mi long.  The tributaries include 40 creeks, 14 brooks, 9 runs, and 2 rivers. By length, the five largest tributaries are Roaring Brook, Spring Brook, the East Branch Lackawanna River, Stafford Meadow Brook, and the West Branch Lackawanna River.  By watershed area, the five largest tributaries are Spring Brook, Roaring Brook, the East Branch Lackawanna River, Leggetts Creek, and the West Branch Lackawanna River.
Answer: 178 mi