Question: In which county is the city sharing a border with the capitol of the first state to formally secede?

Knowledge 1: Charleston, South Carolina
Although the city lost the status of state capital to Columbia in 1786, Charleston became even more prosperous in the plantation-dominated economy of the post-Revolutionary years. The invention of the cotton gin in 1793 revolutionized the processing of this crop, making short-staple cotton profitable. It was more easily grown in the upland areas, and cotton quickly became South Carolina's major export commodity. The Piedmont region was developed into cotton plantations, to which the sea islands and Lowcountry were already devoted. Slaves were also the primary labor force within the city, working as domestics, artisans, market workers, and laborers. [SEP] Knowledge 2: WWNQ
WWNQ is a radio station licensed to Forest Acres, South Carolina, serving the Columbia, South Carolina market. Owned by Midlands Media Group LLC, the station broadcasts a country music format branded as 94.3 The Dude. [SEP] Knowledge 3: Forest Acres, South Carolina
Forest Acres is a city in Richland County, South Carolina, United States. The population was 10,361 at the 2010 census. It is part of the Columbia, South Carolina, Metropolitan Statistical Area. [SEP] Knowledge 4: Military history of the United States
Sectional tensions had long existed between the states located north of the Mason–Dixon line and those south of it, primarily centered on the "peculiar institution" of slavery and the ability of states to overrule the decisions of the national government. During the 1840s and 1850s, conflicts between the two sides became progressively more violent. After the election of Abraham Lincoln in 1860 (who southerners thought would work to end slavery) states in the South seceded from the United States, beginning with South Carolina in late 1860. On April 12, 1861, forces of the South (known as the Confederate States of America or simply the Confederacy) opened fire on Fort Sumter, whose garrison was loyal to the Union.
Knowledge 1: Charleston, South Carolina
Although the city lost the status of state capital to Columbia in 1786, Charleston became even more prosperous in the plantation-dominated economy of the post-Revolutionary years. The invention of the cotton gin in 1793 revolutionized the processing of this crop, making short-staple cotton profitable. It was more easily grown in the upland areas, and cotton quickly became South Carolina's major export commodity. The Piedmont region was developed into cotton plantations, to which the sea islands and Lowcountry were already devoted. Slaves were also the primary labor force within the city, working as domestics, artisans, market workers, and laborers. [SEP] Knowledge 2: WWNQ
WWNQ is a radio station licensed to Forest Acres, South Carolina, serving the Columbia, South Carolina market. Owned by Midlands Media Group LLC, the station broadcasts a country music format branded as 94.3 The Dude. [SEP] Knowledge 3: Forest Acres, South Carolina
Forest Acres is a city in Richland County, South Carolina, United States. The population was 10,361 at the 2010 census. It is part of the Columbia, South Carolina, Metropolitan Statistical Area. [SEP] Knowledge 4: Australia
Each state and major mainland territory has its own parliament — unicameral in the Northern Territory, the ACT and Queensland, and bicameral in the other states. The states are sovereign entities, although subject to certain powers of the Commonwealth as defined by the Constitution. The lower houses are known as the Legislative Assembly (the House of Assembly in South Australia and Tasmania); the upper houses are known as the Legislative Council. The head of the government in each state is the Premier and in each territory the Chief Minister. The Queen is represented in each state by a governor; and in the Northern Territory, the Administrator. In the Commonwealth, the Queen's representative is the Governor-General.The Commonwealth Parliament also directly administers the following external territories: Ashmore and Cartier Islands; Australian Antarctic Territory; Christmas Island; Cocos (Keeling) Islands; Coral Sea Islands; Heard Island and McDonald Islands; and Jervis Bay Territory, a naval base and sea port for the national capital in land that was formerly part of New South Wales. The external territory of Norfolk Island previously exercised considerable autonomy under the Norfolk Island Act 1979 through its own legislative assembly and an Administrator to represent the Queen. In 2015, the Commonwealth Parliament abolished self-government, integrating Norfolk Island into the Australian tax and welfare systems and replacing its legislative assembly with a council. Macquarie Island is administered by Tasmania, and Lord Howe Island by New South Wales.
Knowledge 1: Charleston, South Carolina
Although the city lost the status of state capital to Columbia in 1786, Charleston became even more prosperous in the plantation-dominated economy of the post-Revolutionary years. The invention of the cotton gin in 1793 revolutionized the processing of this crop, making short-staple cotton profitable. It was more easily grown in the upland areas, and cotton quickly became South Carolina's major export commodity. The Piedmont region was developed into cotton plantations, to which the sea islands and Lowcountry were already devoted. Slaves were also the primary labor force within the city, working as domestics, artisans, market workers, and laborers. [SEP] Knowledge 2: WWNQ
WWNQ is a radio station licensed to Forest Acres, South Carolina, serving the Columbia, South Carolina market. Owned by Midlands Media Group LLC, the station broadcasts a country music format branded as 94.3 The Dude. [SEP] Knowledge 3: Forest Acres, South Carolina
Forest Acres is a city in Richland County, South Carolina, United States. The population was 10,361 at the 2010 census. It is part of the Columbia, South Carolina, Metropolitan Statistical Area. [SEP] Knowledge 4: Confederate Arizona
Confederate Arizona, commonly referred to as Arizona Territory, and officially the Territory of Arizona, was a territory claimed by the Confederate States of America during the American Civil War, between 1861 and 1865. Delegates to secession conventions had voted in March 1861 to secede from the New Mexico Territory and the United States, and seek to join the Confederacy. It consisted of the portion of the New Mexico Territory south of the 34th parallel, including parts of the modern states of New Mexico and Arizona. Its capital was Mesilla along the southern border. The Confederate territory overlapped the Arizona Territory later established by the Union government in 1863.

Answer: Richland County