Question: In what county were The 1981 U.S. Clay Court Championships held?

full_context: Document 1: 1981 U.S. Clay Court Championships – Women's Singles: 1981 U.S. Clay Court Championships – Women's Singles
Document 2: 1981 U.S. Clay Court Championships – Men's Doubles: 1981 U.S. Clay Court Championships – Men's Doubles
Document 3: Carmel, Indiana: Carmel is a suburban city in Hamilton County, Indiana, United States, located immediately north of Indianapolis. It has been one of the fastest-growing communities in the country. In 2012, Carmel was selected as the "Best Place to Live in the United States" by CNN Money magazine, and received the same designation by Niche.com in 2017. The population was 79,191 as of the 2010 and was estimated to be 91,065 in 2016 by the US Census Bureau, making it the fifth-largest city in Indiana.
Document 4: 1981 U.S. Clay Court Championships – Women's Doubles: 1981 U.S. Clay Court Championships – Women's Doubles
Document 5: 1981 U.S. Clay Court Championships – Men's Singles: 1981 U.S. Clay Court Championships – Men's Singles
Document 6: Downtown Indianapolis: Downtown Indianapolis refers to the central business district of Indianapolis, Indiana, United States. The boundaries of downtown Indianapolis have varied over time as the city has grown. The city's original platted area, the Mile Square, (bounded by North, South, East, and West streets) is sometimes used to denote the downtown area. However, the Indianapolis Regional Center Plan, which is the official plan for Downtown Indianapolis, defines the boundaries to be 16th Street on the north, Interstate 65/70 on the east, Interstate 70 on the south and the Belt Railroad on the west. The Regional Center therefore encompasses not only the Mile Square, but also the Indiana University – Purdue University Indianapolis campus, White River State Park, and the Eli Lilly and Company corporate headquarters.
Document 7: Indianapolis: Indianapolis (pronounced ), is the capital and largest city of the U.S. state of Indiana and the seat of Marion County. It is in the East North Central region of the Midwestern United States. With an estimated population of 855,164 in 2016, Indianapolis is the third most populous city in the Midwest and 15th most populous in the U.S. The city is the economic and cultural center of the Indianapolis metropolitan area, home to 2 million people, the 34th most populous metropolitan statistical area in the U.S. Its combined statistical area ranks 27th, with 2.38 million inhabitants. Indianapolis covers 368 sqmi , making it the 16th largest city by land area in the U.S.
Document 8: Fort Wayne, Indiana: Fort Wayne is a city in the U.S. state of Indiana and the seat of Allen County. Located in northeastern Indiana, the city is 18 mi west of the Ohio border and 50 mi south of the Michigan border. With an estimated population of 264,488 in 2016, Fort Wayne is the 77th most populous city in the United States and the second largest in Indiana, after Indianapolis. It is the principal city of the Fort Wayne metropolitan area, consisting of Allen, Wells, and Whitley counties, a combined population of 419,453 as of 2011. In addition to the three core counties, the combined statistical area (CSA) includes Adams, DeKalb, Huntington, Noble, and Steuben counties, with an estimated population of 615,077.
Document 9: Madison, Indiana: Madison is a city in and the county seat of Jefferson County, Indiana, United States, along the Ohio River. Its estimated population was 12,247 as of 2016. Over 55,000 people live within 15 miles of downtown Madison. Madison is the largest city along the Ohio River between Louisville, Kentucky and Cincinnati, Ohio. Madison is one of the core cities of the Louisville-Elizabethtown-Madison metroplex, an area with a population of approximately 1.5 million. In 2006, the majority of Madison's downtown area was designated the largest contiguous National Historic Landmark in the United States—133 blocks of the downtown area is known as the Madison Historic Landmark District.
Document 10: 1981 U.S. Clay Court Championships: The 1981 U.S. Clay Court Championships was a men's Grand Prix and women's Toyota Series tennis tournament held in Indianapolis in the United States and played on outdoor clay courts. It was the 13th edition of the tournament and was held from August 3 through August 9, 1981. Second-seeded José Luis Clerc and top-seeded Andrea Jaeger won the singles titles.
Document 11: 1981 World Championship Tennis Finals: The 1981 World Championship Tennis Finals was a men's tennis tournament played on indoor carpet courts. It was the 11th edition of the WCT Finals and was part of the 1981 Volvo Grand Prix. The tournament was played at the Reunion Arena in Dallas, Texas in the United States and was held from April 27 through May 3, 1981. The winners of the eight WCT tournaments that were part of the 1981 Grand Prix circuit qualified for the tournament augmented by the next best performers in the WCT points standings. Guillermo Vilas qualified by winning the last tournament held just before the WCT Finals, the River Oaks Tournament in Houston, but was unavailable to play. Jimmy Connors withdrew before the tournament due to gastroenteritis and Yannick Noah could not participate due to a shoulder injury. They were replaced by Sandy Mayer and Sam Giammalva respectively. John McEnroe won the title and $100,000 prize money.
Document 12: Columbus, Indiana: Columbus is a city in and the county seat of Bartholomew County, Indiana, United States. The population was 44,061 at the 2010 census. In its built environment, the relatively small city has provided a unique place for noted Modern architecture. Located about 40 miles (64 km) south of Indianapolis, on the east fork of the White River, it is the state's 20th largest city. It is also the principal city of the Columbus, Indiana metropolitan statistical area, which encompasses all of Bartholomew County. Columbus is the birthplace of former Indiana Governor and current Vice President of the United States, Mike Pence.
Document 13: Columbus, Ohio: Columbus ( ) is the capital and largest city of the U.S. state of Ohio. It is the 14th-largest city in the United States, with a population of 860,090 as of 2016 estimates. This makes Columbus the third-most populous state capital in the United States, and the second-largest city in the Midwestern United States, after Chicago. It is the core city of the Columbus, Ohio, Metropolitan Statistical Area, which encompasses ten counties. With a population of 2,021,632, it is Ohio's third-largest metropolitan area.
Document 14: Indiana: Indiana is a U.S. state located in the midwestern and Great Lakes regions of North America. Indiana is the 38th largest by area and the 17th most populous of the 50 United States. Its capital and largest city is Indianapolis. Indiana was admitted to the United States as the 19th U.S. state on December 11, 1816. Indiana borders Lake Michigan to the northwest, Michigan to the north, Ohio to the east, Kentucky to the south and southeast, and Illinois to the west.
Document 15: 1981 Italian Open (tennis): The 1981 Italian Open was a combined men's and women's tennis tournament that was played on outdoor clay courts. For the second time in the history of the tournament the men and women competed in different locations. The men's event was held at the traditional location of Foro Italico in Rome, while the women played in Perugia. It was the 38th edition of the tournament. The men's tournament was part of the 1981 Volvo Grand Prix while the women's tournament was part of the Toyota Series (Category 3). The women's event was played from 4 May through 10 May 1981 while the men's event was organized from 18 May through 24 May 1981. Third-seeded José Luis Clerc won the men's singles title and the accompanying $24,000 first-prize money. The women's singles title was won by first-seeded Chris Evert-Lloyd, her fourth Italian Open title after 1974, 1975 and 1980.
ground_truth: Marion County