Question: In which county is Southern Maryland Electric Cooperative headquartered?

Context paragraphs:
paragraph_text: The Dunbar Hospital was the first hospital for the black community in Detroit, Michigan. It is located at 580 Frederick Street, and is currently the administrative headquarters of the Detroit Medical Society. It was listed on the National Register of Historic Places in 1979.
title: Dunbar Hospital
paragraph_text: Alamnagar (community development block) is one of the administrative divisions of Madhepura district in the Indian state of Bihar. The block headquarters are located at a distance of 58 km from the district headquarters, namely, Madhepura. The name of Alamnagar is named for Shah Alamgir.
title: Alamnagar
paragraph_text: Khong Island or Don Khong is the largest island and the seat of administration in the Si Phan Don riverine archipelago located in the Mekong River, Khong District, Champasak Province, southern Laos.
title: Khong Island
paragraph_text: The Southern Maryland Electric Cooperative (SMECO) is an electric distribution cooperative which is headquartered in Hughesville, Maryland. SMECO serves approximately 161,000 customers in Calvert, Charles, Prince George's, and St. Mary's counties of southern Maryland. Under its rules as a nonprofit cooperative, SMECO passes on its costs to its customer-members without markup or profit.
title: Southern Maryland Electric Cooperative
paragraph_text: Southern California Edison (or SCE Corp), the largest subsidiary of Edison International, is the primary electricity supply company for much of Southern California, USA. It provides 14 million people with electricity across a service territory of approximately 50,000 square miles. However, the Los Angeles Department of Water and Power, San Diego Gas & Electric, Imperial Irrigation District, and some smaller municipal utilities serve substantial portions of the southern California territory. The northern part of the state is generally served by the Pacific Gas & Electric Company of San Francisco.
title: Southern California Edison
paragraph_text: Menteng is an administrative village in the Menteng district of Indonesia. It has a postal code of 10310. It is located on the southern area of the Menteng Project.
title: Menteng, Menteng
paragraph_text: Hylestad is a former municipality in Aust-Agder county, Norway. The former municipality was located in the southern part of the present-day municipality of Valle in the traditional region of Setesdal. It existed from 1915 until its dissolution in 1962. The administrative centre was the village of Rysstad where the Hylestad Church was located.
title: Hylestad
paragraph_text: Hughesville is a census-designated place (CDP) in Charles County, Maryland, United States. The population was 2,197 at the 2010 census. Truman's Place was listed on the National Register of Historic Places in 1988.
title: Hughesville, Maryland
paragraph_text: Kiri Territory is an administrative region in the Mai-Ndombe District of Bandundu Province, Democratic Republic of the Congo. The headquarters is the town of Kiri.
title: Kiri Territory
paragraph_text: Pak Tam Chung () is an area in the southern part of the Sai Kung Peninsula in the New Territories of Hong Kong. It is administratively under the Sai Kung District.
title: Pak Tam Chung
paragraph_text: Campora is a town and "comune" in the province of Salerno, Campania (southern Italy). It is located in the territory of Cilento and as of 2009 its population was of 810.
title: Campora
paragraph_text: The United States Bankruptcy Court for the Southern District of New York is the United States bankruptcy court within the United States District Court for the Southern District of New York. The Southern District of New York is a major venue for bankruptcy, as it has jurisdiction over the corporate headquarters and major financial institutions located in Manhattan.
title: United States Bankruptcy Court for the Southern District of New York
paragraph_text: The Ceres Nunataks () are a group of three nunataks located immediately east of the base of Shostakovich Peninsula in southern Alexander Island, Antarctica. They were mapped by the Directorate of Overseas Surveys from satellite imagery supplied by the U.S. National Aeronautics and Space Administration in cooperation with the U.S. Geological Survey, and named by the UK Antarctic Place-Names Committee after Ceres, one of the asteroids lying between the orbits of the planets Mars and Jupiter.
title: Ceres Nunataks
paragraph_text: Port Blair (pronunciation (help info)) is the capital of the Andaman and Nicobar Islands, a union territory of India situated in the Bay of Bengal. It is also the local administrative sub-division (tehsil) of the islands, the headquarters for the district of South Andaman, and is the territory's only notified town. It houses the headquarters of the Andaman and Nicobar Police and the Andaman and Nicobar Command, the first integrated tri-command of the armed forces of India.
title: Port Blair
paragraph_text: Elk Ridge is a mountain ridge of the Blue Ridge Mountains in Maryland. The ridge is located to the west of South Mountain and runs roughly parallel to it from Rohrersville, in the north, to the Potomac River across from Harpers Ferry, West Virginia, in the south. Across the Potomac the ridge continues as Blue Ridge Mountain in Virginia and West Virginia. The southern end of the ridge, which is part of Harpers Ferry National Historical Park, is known as Maryland Heights.
title: Elk Ridge (Maryland)
paragraph_text: Poum is a commune in the North Province of New Caledonia, an overseas territory of France in the Pacific Ocean. The town of Poum (Latitude: 20° 13' 59" south, longitude: 164° 1' 23" east) is located in the far northwest, located on the southern part of Banare Bay, with Mouac Island just offshore.
title: Poum
paragraph_text: Beryslav Raion (, ) is one of the 18 administrative raions (a "district") of Kherson Oblast in southern Ukraine. Its administrative center is located in the city of Beryslav. Its population was 55,976 as of the 2001 Ukrainian Census. Current population:
title: Beryslav Raion
paragraph_text: Minsk Region or Minsk Voblasć or Minsk Oblast (, "Minskaja vobłasć" ; , "Minskaja oblastj") is one of the regions of Belarus. Its administrative center is Minsk, although it is a separate administrative territorial entity of Belarus. As of 2011, the region's population is 1,411,500.
title: Minsk Region
paragraph_text: Pangi Territory is an administrative area in Maniema Province of the Democratic Republic of the Congo. The headquarters is the town of Pangi.
title: Pangi Territory
paragraph_text: WaterColor is an unincorporated master-planned community located in Seagrove Beach on the Northwest Gulf Coast of Florida, United States near Destin. This Southern resort and residential community was planned by Cooper, Robertson & Partners, under the direction of The St. Joe Company. The St. Joe Company has owned the land since 1927. WaterColor is located in Walton County.
title: WaterColor, Florida

Reasoning steps:
Southern Maryland Electric Cooperative >> headquarters location >>>> Hughesville
Hughesville >> located in the administrative territorial entity >>>> Charles County

Answer: spans: Charles County