A small portion of the City and County of Denver near Four Square Mile is located in Colorado's 6th congressional district.

[4] Only two Republicans have been elected to the seat since the Great Depression: Dean M. Gillespie was the district's representative from 1944 to 1947; and Mike McKevitt from 1971 to 1973, winning thanks to an ideological split among Denver Democrats.

Following the 2000 United States census and consequential redistricting of Colorado's congressional districts, the 1st congressional district consisted of all of the City and County of Denver and parts of Arapahoe County, including parts or all of the cities of Englewood, Cherry Hills Village, Sheridan, Aurora, and Glendale.

Following the 2010 United States census and consequential redistricting of Colorado's congressional districts, the 1st congressional district consisted of all of the City and County of Denver and parts of Arapahoe County including parts or all of the cities of Englewood, Cherry Hills Village, Sheridan, Aurora, and Glendale.

The 1st district also took in additional area in the southwestern suburbs which included parts of Jefferson County and the CDPs of Columbine and Ken Caryl.