Question: Greenwood Heights, Brooklyn is bordered to the west by a canal that is how long?

Context paragraphs:
Brooklyn Community Board 7: Brooklyn Community Board 7 is a New York City community board that encompasses the Brooklyn neighborhoods of Sunset Park, Windsor Terrace, Greenwood Heights and South Park Slope.  It is delimited by Gowanus Bay on the west; by 15th Street and Prospect Park South West on the north; and by Caton Avenue, Fort Hamilton Parkway, 37th Street and 8th Avenue on the east, as well as by the Long Island Rail Road and Bay Ridge R.R. Yards on the south.

25th Street (BMT Fourth Avenue Line): 25th Street is a local station on the BMT Fourth Avenue Line of the New York City Subway.  Located at the intersection of 25th Street and Fourth Avenue in Greenwood Heights, Brooklyn, it is served by the R train at all times.  The D and N trains also stop here during late nights, and a few rush-hour W trains stop here in the peak direction.

Greenwood (Columbia, Missouri): Greenwood, also known as Greenwood Heights, is a historic home located at Columbia, Missouri.  It was built about 1839, and is a two-story, "T"-plan, Federal style red brick farmhouse on a stone foundation.  It is one of the oldest remaining structures in Boone County, Missouri.  Today the house is under private ownership.

Upper Brooklyn: Upper Brooklyn or Brooklyn Heights is a neighborhood on South Hill in Minot, North Dakota.  The neighborhood consists of the sections of the Brooklyn Addition that are not part of Downtown Minot.  The High Third neighborhood, the Lower Brooklyn neighborhood and the area around the Minot Municipal Auditorium, which were part of the Brooklyn Addition, are considered part of the downtown area.  Upper Brooklyn is bordered by downtown and the BNSF railroad tracks to the north, Minot High School's Magic City Campus to the west, Eleventh Avenue SW to the south and South Broadway and Lower Brooklyn to the east.  The neighborhood is approximately 0.46 square kilometers.  The neighborhood is home to the Scandinavian Heritage Park and Jim Hill Middle School.

Gowanus Canal: The Gowanus Canal is a canal in the New York City borough of Brooklyn, on the westernmost portion of Long Island.  Connected to Gowanus Bay in Upper New York Bay, the canal borders the neighborhoods of Red Hook, Carroll Gardens, and Gowanus, all within South Brooklyn, to the west; Park Slope to the east; Boerum Hill and Cobble Hill to the north; and Sunset Park to the south.  It is 1.8 mi long.  There are seven bridges over the canal, carrying Union Street, Carroll Street (a landmark), Third Street, Ninth Street, Hamilton Avenue, the Gowanus Expressway, and the IND Culver Line of the New York City Subway.

Sunset Park, Brooklyn: Sunset Park is a neighborhood in the southwestern part of the New York City borough of Brooklyn.  It is bounded by Park Slope, Greenwood Heights and Green-Wood Cemetery to the north, Borough Park to the east, Bay Ridge to the south, and Upper New York Bay to the west.  Because it was once close to the southern boundary of the City of Brooklyn, Sunset Park is considered to be part of South Brooklyn.  However, until the 1960s, the northern part of Sunset Park was considered to be part of Gowanus, and the southern part was included in Bay Ridge.  The neighborhood received its own name in that decade.

Greenwood Heights, Brooklyn: Greenwood Heights is a neighborhood in the New York City borough of Brooklyn that takes part of its name from the neighborhood proximity to the Green-Wood Cemetery.  Greenwood Heights is a part of Brooklyn Community Board 7 along with Windsor Terrace, Sunset Park and South Park Slope.  The much-debated borders are, roughly, the Prospect Expressway to the north, Gowanus Canal to the west, Eighth Avenue to the east, and 39th Street to the south (southern boundary of the Green-Wood Cemetery and northern boundary of the 36th-38th Street Yard and South Brooklyn Railway).

Greenwood, Clarksville, Tennessee: Greenwood is a neighborhood in the southern part of the city of Clarksville, Tennessee, USA.  Located directly south of downtown, Greenwood is often defined as the area delimited by South Riverside Drive to the west, the Mason Rudolph golf course to the east, Ashland City Road (US-41A Bypass/TN-12) to the south, and Crossland Avenue to the north.  It is one of the oldest neighborhoods in the city of Clarksville.  The cemetery that lies within the community, and also bears its name, is one of the oldest in the state of Tennessee, and is the final resting place of Frank Sutton of Sgt. Carter fame from the show "Gomer Pyle, U.S.M.C.".  Olympic gold medalist Wilma Rudolph is also buried in Greenwood at a much smaller cemetery, adjacent to the Mason Rudolph golf course.  In the early 21st century, the neighborhood had declining conditions of some of its older homes and rising crime rates.  The Summit Heights housing project is located in Greenwood, as are the Montgomery County Alternative School, CMCSS headquarters, the Clarksville-Montgomery County Library, and a former boot factory which burned down in 2006.

Prospect Avenue (BMT Fourth Avenue Line): Prospect Avenue is a local New York City Subway station on the BMT Fourth Avenue Line in Brooklyn.  It is located at Prospect Avenue and Fourth Avenue near the convergence of Gowanus, Greenwood Heights, Park Slope, and South Park Slope.  It is temporarily closed from June to December 2017, but under its normal service pattern is served by the R train at all times.  The D and N trains also stop here during late nights, and a few rush-hour W trains stop here in the peak direction.

Lake Tohopekaliga: Lake Tohopekaliga Tohopeka ([from tohopke /(i)to-hó:pk-i/ fence, fort]); Tohopekaliga [from tohopke /(i)to-hó:pk-i/ fence, fort + likv /léyk-a/ site], also referred to as Lake Toho, West Lake, or simply Toho, native name meaning "we will gather together here", is the largest lake located in Osceola County, Florida, United States.  It is the primary inflow of Shingle Creek, which rises in Orlando.  It covers 22700 acre , and spans 42 mi in circumference.  It is linked to East Lake Tohopekaliga by Canal 31 (St. Cloud Canal).  The canal is 3 mi long and runs through western St. Cloud.  South Port canal is located at the southern tip of the lake and links it to Cypress Lake.  It is 4 mi long.  Lake Toho is bordered on the northern shore by Kissimmee, on the eastern shore by Kissimmee Park, and South Port on the southern shore.  Lake Tohopekaliga is known for its bass fishing and birdwatching.  Lakefront Park is located at the north end of the lake and borders Lakeshore Blvd.  Lakefront Park has a scenic walking path with benches where visitors may view the area's wide array of waterfowl, alligators, turtles and others.  Lakefront park also has a miniature lighthouse, a children's playground area, and is bordered on its west end by Big Toho Marina.

Supporting paragraphs: Greenwood Heights, Brooklyn Gowanus Canal
Answer: 1.8 mi