Rock County is located in the south-central portion of the State of Wisconsin, forming a portion of the State’s southern boundary, approximately equidistant from Lake Michigan and the Mississippi River.  The County’s population was estimated at 160,331 in 2010 and the County is projected to have approximately 26,000 additional residents by 2035.  The County covers 721 square miles, containing six Cities, three Villages, and 20 Towns, and multiple unincorporated hamlets.  The County’s Cities include Janesville, Beloit, Edgerton, Milton, Evansville, and Brodhead.  The City of Janesville serves as the County seat, is located in the County’s central portion, and is the largest municipality in the County with a population estimated at over 63,575 in 2010.  The County’s Villages include Clinton, Orfordville, and Footville.

The County is surrounded by vibrant rural communities and burgeoning urban areas. The County is bordered by Wisconsin counties, Dane and Jefferson to the north, Green to the west, and Walworth to the east, and Illinois’ Counties Boone and Winnebago to the south. The rapidly growing Wisconsin State capital the City of Madison, with an estimated population of over 233,209 people in 2010, is 30 miles to the County’s northwest.  Wisconsin’s largest city, Milwaukee, with a metropolitan area containing over 1,555,908 inhabitants in 2010, lies 70 miles east of the County and Rockford, Illinois’ third largest city with an estimated population of over 152,871 residents in 2010 is 30 miles south.  Additionally, Chicago, Illinois, the country’s third largest metropolitan area with a population of over 9,580,609 inhabitants, is 80 miles to the County’s south. The County is connected to these urban areas and other regional, State, and national locations by a vast road network, including U.S. Interstates 90/39 and 43, and U.S. Highways 51 and 14.  

The County’s physical geography is varied.  The County’s main waterway, the Rock River, bisects the County from north to south, running from Lake Koshkonong in the north-central portion of the County, through the Cities of Janesville and Beloit.  The County is located in twelve base watersheds, all components of the Lower Rock Basin, which in turn is part of the Mississippi River Basin.  The County’s defining geologic feature is the end moraine, a remnant of the last glacial advance (Wisconsin Glaciation) approximately 10,000 years ago.  The County’s glacially formed kettle-moraine landscape is characterized by varying topography and drainage patterns, and uneven hills and ridges. 

The County’s Cities and urban areas are home to diverse and unique commercial and industrial sectors, historic and cultural attractions, natural resources, and public and residential areas.  The Cities of Janesville and Beloit both house substantial industrial sectors.  Health care service entities, including Mercy Health System Corporation of Janesville, St. Mary's Hospital/DeanCare Services and Beloit Memorial Hospital Incorporated, also employ a large segment of the County’s labor force, as do various forms of government, including the County and the City of Janesville and Beloit school districts.  The County’s many historic and cultural attractions include the City of Evansville historic district, Beloit College (an acclaimed liberal arts institution located in the City of Beloit) and the City of Janesville’s Rotary Botanical Gardens and Tallman House (an exceptional example of Italian villa style architecture from the mid 1850’s).  Additionally, the Cities of Janesville and Beloit have a combined symphony orchestra, as well as individual performing arts centers.  The Rock County Fair and Riverfest are regional cultural celebrations held every summer in the Cities of Janesville and Beloit respectively.  These Cities both have extensive park and open space networks, including portions of the Ice Age National Scenic Trail, a Statewide trail commemorating the State’s geologic history.  Additionally, the Rock River runs through these Cities, offering opportunities for recreation, land preservation, and highly-valued residential, commercial, and industrial development.  Historic and modern neighborhoods, comprising single and multi-family residences, are interspersed throughout the County’s Cities and urban areas.

The County’s rural areas, including its Towns and Villages, are home to a wide variety of natural resources, historic and cultural attractions, and public and residential areas as well. The County’s rural land base and its rich soils are predominately utilized for agriculture production.  As the County’s urban area industries drive regional economic growth, so to does the County’s rural agriculture production, providing diversification and balance.  Various crops are cultivated in the County’s rural areas, including corn and soybeans.  The County’s crop market value ($63.5 million) in 2002 was fifth among all Wisconsin counties.  Milk cattle, hogs, sheep, and goats are predominant livestock types reared in the County.  County parks, including Magnolia Bluff, home to a unique scenic overlook, scattered woodlands, Lake Koshkonong, the Rock River, and various other waterways provide the County’s rural areas with recreation, and land preservation and development opportunities.