Question: How many miles does the route that the Kenmore Square is the eastern terminus for span?

Context paragraphs:
Blandford Street (MBTA station): Blandford Street is a surface-level tram station on the MBTA's Green Line "B" Branch located in Boston, Massachusetts.  The station is located in the center median of Commonwealth Avenue at Silber Way and Blandford Mall, about 2 blocks west of Kenmore Square, near the east end of Boston University.  The station consists of two low side platforms, which serve the "B" Branch's two tracks.  The station is the first station outbound on the "B" Branch after it splits off from the "C" and "D" Branches at Kenmore.

U.S. Route 20 in Massachusetts: The cross-country U.S. Route 20 runs its easternmost 153 mi in the U.S. state of Massachusetts.  The highway crosses the state border from New Lebanon, New York into Hancock, Massachusetts, and runs eastward into Boston, where it ends at Route 2 in Kenmore Square.  It spends the vast majority of its journey paralleling the Massachusetts Turnpike, which has largely superseded US-20 for through travel.  Still, US-20 directly serves many towns and local business areas which the Turnpike bypasses.

Kenmore (MBTA station): Kenmore is a light rail station on the MBTA Green Line, located under Kenmore Square in the Fenway/Kenmore neighborhood of Boston, Massachusetts.  The station opened on October 23, 1932 as a one-station extension of the Boylston Street Subway to relieve congestion in the square.  Kenmore is the primary station for passengers wishing to visit Fenway Park, located just one block away.  However, some sports fans exit at Fenway station despite its longer distance from the stadium, bypassing congestion in Kenmore Square.

Kenmore Square: Kenmore Square is a square in Boston, Massachusetts, United States, consisting of the intersection of several main avenues (including Beacon Street and Commonwealth Avenue) as well as several other cross streets, and Kenmore Station, an MBTA subway stop.  Kenmore Square is close to or abuts Boston University and Fenway Park, and it features Lansdowne Street, a center of Boston nightlife, and the Citgo sign.  It is also the eastern terminus of U.S. Route 20, the longest U.S. Highway.

Yawkey (MBTA station): Yawkey is a commuter rail station on the MBTA Commuter Rail Framingham/Worcester Line, located in the Fenway-Kenmore neighborhood of Boston, Massachusetts near Kenmore Square.  The station sits below grade between Beacon Street and Brookline Avenue, next to the Massachusetts Turnpike.  Yawkey station was originally opened as an infill station in 1988, for limited service to Boston Red Sox games at Fenway Park.  Regular commuter service began in 2001 for riders headed to Boston University, Kenmore Square, and the Longwood Medical and Academic Area.

Pennsylvania Route 999: Pennsylvania Route 999 (PA 999) is a 9.44 mi , east–west state highway located in western Lancaster County, Pennsylvania.  The western terminus is at PA 441, which has its southern terminus at this intersection, in Washington Boro.  The eastern terminus is at PA 462 in Lancaster.  PA 999 heads east from Washington Boro to rural areas to Millersville.  Upon reaching Millersville, the route heads into developed areas and turns northeast, crossing PA 741.  PA 999 continues northeast to its eastern terminus.  The route is a two-lane undivided road its entire length.  Between Millersville and Lancaster, the route follows a 19th-century private turnpike that runs along the Manor Road that was created in 1742.  PA 999 was designated in 1928 between Millersville and U.S. Route 30 (US 30)/PA 1 (now PA 462) in Lancaster.  The route was extended west to its current terminus at PA 441 in the 1950s.

U.S. Route 20: U.S. Route 20 (US 20) is an east–west United States highway that stretches from the Pacific Northwest all the way to New England.  The "0" in its route number indicates that US 20 is a coast-to-coast route.  Spanning 3365 mi , it is the longest road in the United States, and the route roughly parallels that of Interstate 90 (I-90).  There is a discontinuity in the official designation of US 20 through Yellowstone National Park, with unnumbered roads used to traverse the park.

Brookline Avenue: Brookline Avenue is a principal urban artery in the city of Boston, Massachusetts, terminating in the town of Brookline.  The Landmark Center, Fenway Park, Emmanuel College, Longwood Medical and Academic Area and Kenmore Square are sites along its length.  It runs from Kenmore Square in the Fenway-Kenmore neighborhood, forming a 1.5-mile straight line to its other terminus at Washington Street in the Brookline Village neighborhood of Brookline, Massachusetts.

Missouri Route 120: Route 120 is a short highway in Holt County.  Its eastern terminus is at Route B about eight miles (13 km) northeast of Oregon.  Its western terminus is at U.S. Route 59 about three miles (5 km) west of its eastern terminus.  No towns are on the highway.

Fenway–Kenmore: Fenway–Kenmore is an officially recognized neighborhood of Boston, Massachusetts.  While it is considered one neighborhood for administrative purposes, it is composed of numerous distinct sections (East Fenway, West Fenway, Audubon Circle, Kenmore Square) that, in casual conversation, are almost always referred to as "Fenway" "the Fenway," "Kenmore Square," or "Kenmore."  Furthermore, the Fenway neighborhood is divided into two sub-neighborhoods commonly referred to as East Fenway/Symphony and West Fenway.

Supporting paragraphs: Kenmore Square U.S. Route 20
Answer: 3365