Connersville is a city in Fayette County, Indiana, United States, 66 miles (106 km) east by southeast of Indianapolis. The population was 13,324 at the 2020 census. The city is the county seat of and the only incorporated town in the county. The city is in the center of a large rural area of east central Indiana; the nearest significant city is Richmond, 26 miles (42 km) to the northeast by road. Connersville is home to Fayette county's only high school. The local economy relies on manufacturing, retail, and healthcare to sustain itself. However, there has been a consistent decline in both employment and population since the 1960s, placing it among the least affluent areas in the state of Indiana, as indicated by measures such as median household income and other economic indicators.

The city is among the oldest cities in Indiana and the former Indiana Territory, having been established in 1813 by its namesake, John Conner.

Connersville is named for settler John Conner, older brother of William Conner, an early Indiana settler and politician. There was also, at least through 1795, Connerstown, a small Shawnee village near Lancaster, Ohio, named for John's father, Richard Conner.

The Whitewater River valley running north–south through eastern Indiana and southwestern Ohio was created by the Late Wisconsin Glaciation ending 13,600 years ago. Fayette County was at the southern fringe of the glaciation at that time. The Ice Age was punctuated by several prolonged warm periods during which the glaciers disappeared entirely from the temperate latitudes and a climate similar to modern times or even warmer prevailed. The flood waters produced resulted in lakes; breaching of the lakes resulted in rivers and streams carving its hills and valleys.

In the Northwest Territory during the latter half of the 18th century, the Miami Indians were dominant in the region, but the Potawatomi and Shawnee had a significant presence. Delaware Indians, displaced from their eastern homelands by European settlement, migrated west and settled along the forks of the Whitewater River. The Whitewater and Ohio River valleys had also been inhabited earlier by other Native Americans called mound builders for their characteristic large burial mounds still in evidence.

The geological aspects of the Whitewater River Valley contributed to early settlement after defeat of the Delaware Indians by General Anthony Wayne at Fallen Timbers in 1794, followed on August 3, 1795, by the Treaty of Greenville ceding most of Ohio and a sliver of southeastern Indiana to the United States. The valley, running south and southeasterly from east central Indiana to the Ohio River Valley, provided a convenient conduit for migration through Fort Washington (Cincinnati) from points east, settlements on the Ohio River, and settlers from Kentucky to northern and central Indiana Territory. Squatters engaged in agriculture and trading were occupying federal lands well before land sales in Indiana Territory began in 1801. An Indian trail paralleled the river from the Ohio Valley northward to the forks, then went along the East Fork to Eli Creek, thence taking a northwesterly direction passing through what was later Connersville, and then on to the Delaware villages strung along the White River from north of modern-day Indianapolis to modern Muncie.

John Conner, his brother William, and others arrived in the Whitewater Valley from south central Ohio in 1802, establishing a fur trading post in an unpopulated area near what was later to become Cedar Grove on the Whitewater River (Franklin County) at the very fringe of the European penetration into the wilderness of Indiana. By 1808, as a result of reduction of Indian hunting grounds by treaty, the trading post, known as "Conner's Post", had been relocated 20 miles (32 km) north at the Whitewater River junction with an Indian trail between the Ohio River 70 miles (110 km) to the southeast and hunting grounds to the north. According to research by J. L. Heineman, the trading post was located in the middle of what is now Eastern Avenue, at the west end of Charles Street. At that time, the region was inhabited by Delaware Indians. In 1809, the Treaty of Fort Wayne was signed, by the terms of which the land locally known as the "Twelve Mile Purchase" was ceded by the Indians to the government. This tract included a strip twelve miles (19 km) in width lying west of the 1795 Greenville treaty line that ran from the midpoint of the Indiana/Ohio border southwest to the Ohio River, cutting off a thin wedge of southeastern Indiana. The strip included most of Fayette County except the extreme northern portion (part of the later "New Purchase"). Sales of public land by the United States government in Indiana began in 1801. In that year the Cincinnati, Ohio, Land Office began selling land in a wedge of government land in southeastern Indiana known as the "Gore" (organized as Dearborn County in 1803) which included all of what became Fayette County. Conner obtained title to his plat in 1811.

The exodus of the Delaware Indians from Indiana after the War of 1812, completed by June 1813, deprived John Conner of his field for trading. After 1812, Indian resistance to settlement in the Indiana Territory became nearly non-existent, so Conner busied himself with another task.