Stillman Valley lies in a broad valley in the Rock River basin. Throughout it's history, it has remained a quiet town and due to the presence of two railroads it became a natural place for farmers to transport their grain for eventual shipment by rail to other areas. Stillman Valley has two grain elevators but only one existing rail link. It has a population of about 1000. Many of it's residents commute to nearby Rockford for employment and shopping. It is positioned 42.10 degrees north of the equator and 89.17 degrees west of the prime meridian. Stillman Valley is approximately 20 miles South of Rockford.

Stillman Valley is in Marion Township and Ogle County. Ogle County was formed in 1836 from a part of Jo Daviess County. Ogle County is the seventeenth (17th) largest county in Illinois, comprising twenty-four (24) townships totaling 757 square miles or 499,320 acres. The highest elevation is 1,023 ft. above mean sea level in the NE 1/4 of Section 3 Maryland Township along a ridge known as “hardpan ridge”, which is about two (2) miles east of Baileyville on Montague Road. The lowest elevation is 649.6 ft. above mean sea level, located at the Rock Rivers’ exit from Ogle County into Lee County in Section 8 of Grand Detour Township. The average elevation in most of the County is between 700 and 900 ft. above mean sea level.

Prior to settlement, the area of present-day Ogle County consisted of approximately 58 percent prairie, 27 percent timber, and the remainder was wetland and bottom land forest. 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.