Oklahoma City (/oʊkləˌhoʊmə -/ (listen)), officially the City of Oklahoma City, and often shortened to OKC, is the capital and largest city of the U.S. state of Oklahoma. The county seat of Oklahoma County, it ranks 20th among United States cities in population, and is the 8th largest city in the Southern United States. The population grew following the 2010 census and reached 687,725 in the 2020 census. The Oklahoma City metropolitan area had a population of 1,396,445, and the Oklahoma City–Shawnee Combined Statistical Area had a population of 1,469,124, making it Oklahoma's largest municipality and metropolitan area by population.
Oklahoma City's city limits extend somewhat into Canadian, Cleveland, and Pottawatomie counties, though much of those areas outside the core Oklahoma County area are suburban tracts or protected rural zones (watershed). The city is the eighth-largest in the United States by area including consolidated city-counties; it is the second-largest, after Houston, not including consolidated cities. The city is also the second largest by area among state capital cities in the United States, after Juneau, Alaska.
Lu'an is a prefecture-level city in Anhui Province. Located in the west of Anhui Province, known as "Gaocheng" for short, located between the Yangtze River and the Huaihe River, the northern foot of the Dabie Mountains, the west wing of the Yangtze River Delta economic zone, the geographical meaning of "West Anhui" specifically refers to Liu'an. Liu'an is located in Jianghuai, with Wu Yue in the east, Jingchu in the west and the Central Plains in the north; the terrain is high in the southwest and flat in the northeast, showing a trapezoidal distribution; it belongs to the transition zone from the north subtropical zone to the warm temperate zone, with significant monsoons and four distinct seasons. In 2017, the city has a total area of 15451 square kilometers and a registered population of 5.882 million. It has jurisdiction over 3 districts and 4 counties. The name of Lu'an began with Emperor Wu of the Han Dynasty, taking the first words of six counties in Hengshan, Anfeng and Anfeng, and other Hengshan countries as Lu'an, with the meaning of "peace in six places, never rebellion". Because Shun Feng Gao Tao in six, so later generations called Liu'an