Question: How long is the interstate that Mountain Empire Airport is situated next to?
Context: Verona Villafranca Airport (IATA: VRN, ICAO: LIPX) , also known as Valerio Catullo Airport or "Villafranca Airport", is located 10 km southwest of Verona, Italy.  The airport is situated next to the junction of A4 Milan-Venice and A22 Modena-Brenner motorways.  It serves a population of more than 4 million inhabitants in the provinces of Verona, Brescia, Mantua (Mantova) and Trentino-Alto Adige/Südtirol. Mountain Empire Airport (ICAO: KMKJ, FAA LID: MKJ) is a public use airport in Smyth County, Virginia, United States.  It located nine nautical miles (10 mi, 17 km) northeast of the central business district of Marion (in Smyth County) and 13 nautical miles (15 mi, 24 km) west of Wytheville (in Wythe County).  The airport is situated between Interstate 81 and U.S. Route 11 (Lee Highway), near Groseclose.  It is owned by Smyth Wythe Airport Commission. Empire Airport (FAA LID: 18NV (formerly 1A8)) is a public use airport located at the northwest corner of the former town of Empire, in Washoe County, Nevada, United States.  It is owned by the US Bureau of Land Management, and leased to U.S. Gypsum Company. Old Airport is an area of Doha, Qatar.  The district is located close to the site of Doha's old international airport servicing Qatar before the construction of the Hamad International Airport.  Running through the district Old Airport St, around which a large number of businesses and retailers cater to the residents of the area.  The first mall constructed in Qatar is also located within the district, situated next to the congested Najma roundabout. Jach'a Wankarani (Aymara "jach'a" big, "wankara" a kind of drum, "-ni" a suffix to indicate ownership, "the one with a big drum" or "the big one with a drum", also spelled "Jachcha Huancarani, Jacha Huancarani") is a mountain in the Chilla-Kimsa Chata mountain range in the Andes of Bolivia, about 4040 m high.  It is located in the La Paz Department, Los Andes Province, Laja Municipality, near Saqaqani "(Sacacani)".  Jach'a Wankarani lies north-east of the mountain Phujtir Pata Punta.  It is situated next to the mountain Wankarani (4009 m ). Interstate 81 (I-81) is an 855 mi highway.  In the U.S. state of Virginia, I-81 runs for 324.92 mi , making the portion in Virginia longer than any other state's portion.  It is also the longest Interstate highway within the borders of Virginia.  It stretches from the Tennessee state line near Bristol to the West Virginia state line near Winchester. The Mountain Empire is a rural area in southeastern San Diego County, California.  The Mountain Empire subregion consists of the backcountry communities in southeastern San Diego County.  The area is also sometimes considered part of the East County region of San Diego County. Empire Airport (FAA LID: Y87) is a public use airport located three nautical miles (6 km) southeast of the central business district of Empire, a village in Empire Township, Leelanau County, Michigan, United States.  The airport is owned by the village and township. Sydney (Kingsford Smith) Airport (colloquially Mascot Airport, Kingsford Smith Airport, or Sydney Airport; IATA: SYD, ICAO: YSSY ; ) is an international airport in Sydney, Australia located 8 km (5 mi) south of Sydney city centre, in the suburb of Mascot.  It is the primary airport serving Sydney, and is a primary hub for Qantas, as well as a secondary hub for Virgin Australia and Jetstar Airways.  Situated next to Botany Bay, the airport has three runways, colloquially known as the east–west, north–south and third runways. The NWA Mountain Empire Championship was originally created to replace the NWA Smoky Mountain Television Championship.  On March 24, 2011; Chase Owens defeated Jason Kincaid to become the first champion.  On August 19, 2017; at ReGenesis, promoter Tony Givens announced that NWA Smoky Mountain Wrestling was leaving the NWA thus the promotion was changing their name to Innovate Wrestling and the NWA Mountain Empire Championship Championship was officially retired as a result.  Toby Farley defeated Timmy Lou Retton to become the Interim Innovate Wrestling United States Champion.
Answer: 855 mi