Connecticut's 5th congressional district is a congressional district in the U.S. state of Connecticut. Located in the western part of the state and spanning across parts of Fairfield, Litchfield, New Haven, and Hartford Counties, the district runs from Meriden and New Britain in central Connecticut, westward to Danbury and the surrounding Housatonic Valley, encompassing the Farmington Valley, Upper Naugatuck River Valley, and the Litchfield Hills. The district also includes most of Waterbury.

Litchfield County is in northwestern Connecticut, United States. As of the 2020 census, the population was 185,186. The county was named after Lichfield, in England. Litchfield County has the lowest population density of any county in Connecticut and is the state's largest county by area.