Ogle County was formed in 1836 from a part of JoDaviess County.
The first session of the Ogle County Commissioners Court was held on January 3, 1837 in Oregon. Oregon was chosen to be the County Seat.
The county courthouse was built in 1891 at a cost of$106,951, and is on the National Register of Historic Places. The interior was renovated in 1984 at a cost of $1,500,000.
There are approximately 30,539 registered voters,and about 27,000 parcels of real estate.
There are three state parks and one state forest in Ogle County.
The county-owned Weld Park is located about two and a half miles southwest of Stillman Valley.
Camp McCormick Girl Scout camp and Lowden Boy Scout camp are located in Ogle County.
There are many historic sites in the county, including the John Deere museum in Grand Detour, historic museums in Byron, Rochelle and Oregon. Rochelle is home to a popular railroad park.
Major industries in the county include agriculture,printing, food distribution and processing, implement manufacturing, recreation and tourism. ComEds Byron nuclear power plant is located south of Byron.
In present-day Ogle County, native prairie is all but non-existent, except for a few scattered prairie remnants found mostly along railroad right-of-ways and rocky and/or sandy ridges and hillsides that have not been tilled. The Byron Forest Preserve and Nachusa Grasslands have restored large areas to native prairie.
According to the U.S. Forest Service, in 1985 OgleCounty contained 32,200 acres of forest land, which accounts for 3.8% of the total area of the County. Interestingly, Ogle County presently contains more forest land than at anytime after 1924.