[4] Carlyle is located approximately 50 miles (80 km) east of St. Louis, Missouri, and is home to Illinois' largest man-made lake, Carlyle Lake, and to the General Dean Suspension Bridge, a suspension bridge that is the only one of its kind in Illinois and crosses the Kaskaskia River.

In 1811 or 1812, a man named John Hill built one of several "block" houses along the Goshen Trail, located at what is currently 201 Fairfax Street.

The houses were reportedly built to serve as a line of defense against Native Americans.

In 1816, Charles Slade and two of his brothers reached the John Hill settlement and bought him out.

Charles farmed the land, took over the ferry, and within a year partnered with a man named Hubbard to start the first store, a mercantile business located at what is now 301 Fairfax Street.

Charles Slade donated 20 acres (8.1 ha) of property so that the county seat would be located in Carlyle.

[8] Charles Slade pushed hard for Carlyle to become the state capital of Illinois, but lost by one vote to Vandalia in 1819.

[9] Carlyle is located slightly east of the center of Clinton County at 38°36′46″N 89°22′15″W / 38.61278°N 89.37083°W / 38.61278; -89.37083 (38.612642, -89.370789).

[10] The Kaskaskia River flows through the easternmost part of the city out of Carlyle Dam, located just northeast of the city limits and which impounds Carlyle Lake, the largest lake wholly in Illinois.