Question: Interstate 680 has a southern terminus at the turnpike that is of what length?
Context: New Hampshire Route 16 is a 149.75 mi long north–south highway in New Hampshire.  Much of its length is close to the border with Maine.  The section from Portsmouth to Milton is a controlled-access toll highway known as the Spaulding Turnpike.  Between the Portsmouth Circle and Dover Point, US 4 is also routed along the Turnpike.  Its southern terminus of NH 16 is at the Portsmouth Traffic Circle, intersecting with Interstate 95 and the US 1 Bypass.  The northern terminus is at the Maine state line near Wentworth's Location, where it continues as Maine State Route 16. Pennsylvania Route 407 (PA 407) is a 12.5 mi state highway located in Lackawanna and Susquehanna Counties in Pennsylvania.  The southern terminus is at U.S. Route 6 (US 6)/US 11 in South Abington Township, Pennsylvania near Clarks Summit near the northern terminus of Interstate 476 (I-476), also known as the Pennsylvania Turnpike's Northeast Extension.  The northern terminus is at PA 374 near Glenwood.  PA 407 is a two-lane road that serves Clarks Green and Waverly in northern Lackawanna County.  This route was part of the Philadelphia and Great Bend Turnpike, a turnpike that was built in 1826.  PA 407 was designated in 1928 between US 6/US 11 in Clarks Summit and PA 107 in Fleetville.  The route was extended north to PA 374 in 1961.  PA 407 was rerouted to its current southern terminus in 2004. Interstate 680 (I-680) in the State of Ohio is the primary Interstate Highway passing through Youngstown, Ohio.  Its northern terminus is at Interstate 80 and its southern terminus is at Interstate 76, the Ohio Turnpike. Interstate 470 (I-470) is a 13.72 mi loop highway that bypasses the downtown area of Topeka, Kansas.  I-470 begins at an interchange with Interstate 70 in western Topeka and heads generally southeast, running concurrent with U.S. Route 75 (US-75).  The concurrency with US-75 ends 5.74 mi later at the Burlingame Road interchange.  I-470 becomes part of the Kansas Turnpike at its junction with Interstate 335.  From there, the highway heads generally northeast through the southeastern sections of Topeka.  After traveling 7.03 mi as the Kansas Turnpike, I-470 reaches its eastern terminus with Interstate 70.  The highway has annual average daily traffic values as high as 43,000 west of Gage Boulevard to as low as 10,370 near the eastern terminus with Interstate 70.  As an interstate highway, Interstate 470 is a part of the United States National Highway System.  The non-turnpike portions of the highway are maintained by the Kansas Department of Transportation, while the turnpike portion is maintained by the Kansas Turnpike Authority. State Route 242 (SR 242) is a short three-mile (5 km) connector route that links Interstate 680 north of Pleasant Hill to State Route 4 in Concord.  In 2000, State Route 242 was widened to six through-traffic lanes for the entire route.  Ramp metering is present at all onramps, and is used southbound in the morning and northbound in the evening.  It was signed as part of State Route 24 until ca. 1987.  Currently, along with Interstate 580, State Route 24, Interstate 680, and State Route 4, it serves as the most direct route between the San Francisco Bay Area and the Sacramento River Delta region of Northern California. The New Jersey Turnpike (NJTP), colloquially known to New Jerseyans as "the Turnpike", is a toll road in New Jersey, maintained by the New Jersey Turnpike Authority.  According to the International Bridge, Tunnel and Turnpike Association, the Turnpike is the nation's sixth-busiest toll road and is one of the most heavily traveled highways in the United States.  Having a total length of 122.40 mi , the Turnpike's southern terminus begins at Interstate 295 (I-295) near the border of Pennsville and Carneys Point Townships in Salem County, one mile east of the Delaware Memorial Bridge.  Its northern terminus is located at the George Washington Bridge in Fort Lee, Bergen County.  The Turnpike is a major thoroughfare providing access to various localities in New Jersey, as well as Delaware, Pennsylvania, and New York.  The route divides into four roadways between exit 6 and exit 14, with the inner lanes restricted to carrying only cars, and with the outer lanes for cars, trucks and buses. The Ohio Turnpike, officially the James W. Shocknessy Ohio Turnpike, is a 241.26 mi , limited-access toll highway in the U.S. state of Ohio, serving as a primary corridor to Chicago and Pittsburgh.  The road runs east–west in the northern section of the state, with the western end at the Indiana–Ohio border near Bryan where it meets the Indiana Toll Road, and the eastern end at the Ohio–Pennsylvania border near Petersburg, where it meets the Pennsylvania Turnpike.  The road is owned and maintained by the Ohio Turnpike and Infrastructure Commission (OTIC), headquartered in Berea. Florida's Turnpike, designated as State Road 91 (SR 91) and the Ronald Reagan Turnpike, is a toll road in Florida, maintained by Florida's Turnpike Enterprise (FTE).  Spanning approximately 309 mi along a north–south axis, the turnpike is in two sections.  The SR 91 mainline runs roughly 265 mi , from its southern terminus at an interchange with Interstate 95 (I-95) in Miami Gardens to an interchange with I-75 in Wildwood at its northern terminus.  The Homestead Extension of Florida's Turnpike (abbreviated HEFT and designated as SR 821) continues from the southern end of the mainline for another 48 mi to US Highway 1 (US 1) in Florida City. State Route 164 (SR 164) is a state highway passing through four counties in east-central Ohio.  The route runs in a general southwest to northeast fashion, and is signed north–south accordingly.  The southern terminus is at an intersection with State Route 212 1 mi south of Leesville, and the northern terminus is at Interstate 680 and Western Reserve Road on the Beaver and Boardman township boundary between North Lima and Boardman.  The southern part of the route serves more rural areas while it makes its way through larger villages and cities toward its northern end. State Route 170 (SR 170) is a north–south running state route located in Mahoning and Columbiana counties in northeast Ohio.  It runs within a few miles of the Pennsylvania border for much of its route as it passes though the eastern parts of the two counties.  The southern terminus is at an interchange with U.S. 30, State Route 7, and State Route 11 near Calcutta, and the northern at U.S. 62 in Youngstown.  ODOT extended the northern terminus from the previous point of Interstate 680, changing signs on July 16 and 17, 2008.
Answer: 241.26 mi