Question: The largest city in the county of Gibson is home to an ammunitions plant about how many miles north of Jackson, Tenessee?
Context: Chapman is an unincorporated community located in Lawrence County, Kentucky, United States on the eastern bank of the Levisa Fork River.  It is served by KY Route 2037.  A high volume railway line, operated by CSX Transportation, extends through its limits and continues in a southerly direction throughout southeastern Kentucky to western Virginia and points south.  Although its location is many miles from the nearest industrial employer, the railroad has served the community as a source of employment.  The railroad was first built through the community in 1880 by CSX's predecessor, the Chesapeake and Ohio Railway.  C&O employees who resided in Chapman caught the train as it passed through on its multiple daily runs where they reported to work.  Chapman, Kentucky is named after its first settler and prominent landowner David Chapman (1803–1845), a native of Montgomery, West Virginia.  Many of Chapman's descendants still reside in the community at this time.  Chapmansville, West Virginia, a city located on U.S. Route 119 about forty miles east of Chapman, was established in 1800 by David Chapman's uncle Ned Chapman, as he was its first postmaster and general store operator.  The Chapman surname is an anglicized version of the German name Kaufmann, the German word for merchant.  David Chapman's ancestors originally emigrated to North America from Kaufmann, Germany.  Chapman is located 10 mi south of Louisa, Kentucky. Humboldt is a city in Gibson and Madison counties, Tennessee.  The population was 8,452 at the 2010 census, a decline of 1,015 from 2000.  It is the principal city of and is included in the Humboldt, Tennessee Micropolitan Statistical Area, which is included in the Jackson, Tennessee-Humboldt, Tennessee Combined Statistical Area.  It is Gibson County's largest city and Madison County's second largest city after Jackson. Camp Ravenna Joint Military Training Center, formerly known as the Ravenna Training and Logistics Site and the Ravenna Army Ammunition Plant (RVAAP) and commonly known as the Ravenna Arsenal, is an Ohio Army National Guard military base located between Ravenna and Newton Falls and adjacent to the village of Windham in the U.S. state of Ohio.  Before its present status as a training facility for the Ohio National Guard, Camp Ravenna was a military ammunition production facility for the United States Army.  As an arsenal, the facility was at peak operation during World War II and would serve as an ammunitions plant in various roles until 1992.  Camp Ravenna remains an important part of the history and geography of Portage County, Ohio.  The facility occupies portions of Freedom, Windham, Charlestown, and Paris townships in Portage County, along with part of Braceville Township in Trumbull County. Milan ( ) is the second largest city after Humboldt in Gibson County, Tennessee, and the largest entirely within the county.  It is home to the Milan Army Ammunition Plant, the West Tennessee Agricultural Museum and several historical sites listed on the National Register of Historic Places (NRHP).  The city was the first in Tennessee to begin no-till farming and to flouridate its drinking water.  The Milan Endowment for Growth in Academics (MEGA) was the first private community financial endowment for public schools in Tennessee. Tunstead is a village and a civil parish in the English county of Norfolk.  The village is 10.7 miles north north east of the city of Norwich, 15 miles south south east of Cromer and 129 miles north east of London.  Tunstead is 2.5 miles north of the settlements of Wroxham and Hoveton. Mount Hill rises from the rolling farmland about three miles north west of Cupar in North East Fife, Scotland.  On its summit stands the 29 m high Hopetoun Monument, which is visible for many miles around. Stramshall is a village within the civil parish of Uttoxeter Rural in the county of Staffordshire, England.  The village is 2.1 miles north of the town of Uttoxeter, 16.3 miles north east of Stafford and 143 miles north west of London.  The village lies 0.8 miles north of the A50 that links Warrington to Leicester.  The nearest railway station is at Uttoxeter for the Crewe to Derby line.  The nearest airport is East Midlands Airport. The Gibson Generating Station is a coal-burning power plant located at the northernmost end of Montgomery Township, Gibson County, Indiana, United States.  It is close to the Wabash River, 1.5 miles southeast of Mount Carmel, Illinois, 2 miles south of the mouth of the Patoka River, and 4 miles south of the mouth of the White River.  The closest Indiana communities are Owensville 7.5 miles to the southeast of the plant, and Princeton, 10.5 miles to the east.  With a 2013 aggregate output capacity among its five units of 3,345 megawatts, it is the largest power plant run by Duke Energy, the third-largest coal power plant in the world, and the tenth-largest electrical plant in the United States, With the reduction of Nanticoke Generating Station, it became the largest coal power plant in North America by generated power late in 2012.  Also on the grounds of the facility is a 3000 acre large man-made lake called Gibson Lake which is used as a cooling pond for the plant.  Neighboring the plant is a Duke-owned, publicly accessible access point to the Wabash River near a small island that acts as a wildlife preserve.  This is the nearest boat-ramp to Mount Carmel on the Indiana side of the river.  Located immediately south of Gibson Lake, the plant's cooling pond, is the Cane Ridge National Wildlife Refuge, the newest unit of the Patoka River National Wildlife Refuge and Management Area.  Opened in August 2006, this 26 acre area serves as a nesting ground for the least tern, a rare bird.  Cane Ridge NWR is reportedly the easternmost nesting ground for the bird in the U.S.  The Gibson Generating Station is connected to the power grid via five 345 kV and one 138 kV transmission lines to 79 Indiana counties including the Indianapolis area and a sixth 345 kV line running from GGS to Evansville and Henderson, owned by Vectren and Kenergy. Milan Army Ammunition Plant (MLAAP) is an ammunition plant of the United States Army near Milan, Tennessee and about 23 miles (37 km) north of Jackson, Tennessee. Gibson Lake is the cooling pond for Duke Energy Indiana's Gibson Generating Station.  Measuring at around 3500 acre , it is the largest lake in Indiana built completely above ground, its shores consisting of rock levees on all but two of the lake's six sides both of which were also built up to build the power plant.  Opened to fishing in 1978, Gibson Lake had been a prime source of bass and several types of catfish, bluegill, and carp.  The lake was closed to fishing in 2007, due to elevated levels of selenium found in the water of the lake.  The only entrance to Gibson Lake is the lake's boat ramp, located due southeast of the plant on Gibson County Road 975 South.
Answer: 23