Janesville is a city in, and the county seat of Rock County, Wisconsin, United States. The population was 65,615 at the 2020 census, and was estimated at 66,428 in 2024, It is located along the Rock River in southern Wisconsin.
History
The area that became Janesville was the site of a Ho-Chunk village named (Round Rock) up to the time of Euro-American settlement. In the 1825 Treaty of Prairie du Chien, the United States recognized the portion of the present city that lies west of the Rock River as Ho-Chunk territory, while the area east of the river was recognized as Potawatomi land. Following the Indian Removal Act of 1830 and the Black Hawk War of 1832, both nations were forced to surrender this land to the United States.
American settlers John Inman, George Follmer, Joshua Holmes, and William Holmes Jr. built a crude log cabin in the region in 1835. Later that year, one key settler, Henry F. Janes,
Despite being named after a Virginian, Janesville was founded by old stock Yankee immigrants, descended from the English Puritans who settled New England in the 1600s. The completion of the Erie Canal caused a surge in New Englander immigration to what was then the Northwest Territory. Some of them were from upstate New York, and had parents who had moved to that region from New England shortly after the Revolutionary War. New Englanders, and New England transplants from upstate New York, were the vast majority of Janesville's inhabitants during the first several decades of its history. Land surveys encouraged pioneers to settle in the area among the abundance of fertile farmland and woodlands. Many of these early settlers established farms and began cultivating wheat and other grains.
Some of the key settlers hailed from the burned-over district of western New York State, (an area notable for being a part of the Christian revival movement known as the Second Great Awakening). Some of those in that revival movement were also active in the abolitionist and women's rights movements.
After the Civil War, Janesville's agriculture continued to surge and a greater demand for new farming technology led to the development of several foundries and farm machine manufacturers in the area, including the Janesville Machine Company, and the Rock River Iron Works. With the boom in the farm service sector and establishment of a rail system, Janesville soon began to ship goods to and from prominent eastern cities, including New York, Boston, and Philadelphia. After decades of rigorous grain farming, the soil quality around Janesville began to degrade. Farmers responded to this by planting tobacco, which became one of the most profitable and prolific crops grown in Wisconsin during the late 19th century. Only one German-language newspaper was founded in the town; it was known as The Janesville Journal, and began in 1889, printing for only a few years.
In the late 19th and early 20th centuries, the Milwaukee Road and Chicago and North Western railroads had freight and passenger rail connections to the city. Passenger rail service continued until 1971.
One of the key developments in Janesville's history was the establishment of a General Motors plant in 1919. The plant was initially established to produce Samson tractors, a company acquired by GM co-founder William C. Durant. Durant was encouraged by Joseph Craig, the president of Janesville Machine, to build a plant to produce the Samson tractors in Janesville, to which Durant agreed. In the years following World War I, the demand for tractors plummeted and the plant shifted its focus to the production of automobiles.
A tree that once stood in downtown Courthouse Park was the site of a lynch mob that, on their second attempt, having been rebuffed by an opposing crowd the day before, hanged a convicted murderer in 1859. Janesville had a "Peace Park" with a playground and a peace pole, which when constructed was the tallest in the world and is now the second tallest.
Janesville developed its first flag in 2015 in a design contest held in Janesville's schools. The flag represents the community's past, present, and future, with 1853 representing the year Janesville was incorporated, four stars symbolizing the city's four original wards, a green background standing for the community's agricultural industry, and black representing both the rich soil for which Janesville is known, and the smoke that billowed from smokestacks as the community developed a manufacturing economy. The tree in the center is the city's logo, representing Janesville's slogan, "Wisconsin's Park Place."
Geography
thumb|Rock River in downtown Janesville
According to the United States Census Bureau, the city has a total area of , of which is land and (1.71%) is water.