Route 9 is a 40.89-mile-long (65.81 km) expressway running from Interstate 95 (I-95) in Old Saybrook north to I-84 in Farmington.

It connects the Eastern Coastline of the state along with the Lower Connecticut River Valley to Hartford and the Capital Region.

It runs northwesterly, parallel to the river for approximately 25 miles (40 km) between Old Saybrook and Route 99 in Cromwell.

After its junction with Interstate 91 in Cromwell, Route 9 continues westward then northward, running through the Hartford area towns/cities of Berlin, New Britain, Newington, and Farmington.

The at-grade portion is 0.52 miles (0.84 km) in length and consists of two intersections with traffic lights (signed as exits 23C and 24), and one median break to allow access to and from Miller Street.

The section from I-91 in Cromwell to exit 24 in Berlin is known as the Korean War Veterans Memorial Highway.

The section from Route 175 in Newington to the junction with I-84 is known as the Iwo Jima Memorial Expressway.

In 1979, the eastern end of the Route 72 freeway up to the Berlin Turnpike was completed, including a connector to the planned alignment of Interstate 291 in New Britain.