Following the 1990 U.S. census and associated realignment of Colorado congressional districts, the 2nd congressional district consisted of Boulder, Clear Creek, and Gilpin counties, as well as portions of Adams, and Jefferson counties.
Following the 2010 U.S. census and associated realignment of Colorado congressional districts, the 2nd congressional district consisted of Broomfield, Clear Creek, Gilpin, Grand and Summit counties; most of Boulder and Jefferson counties; and portions of Eagle, Larimer and Weld counties. Following the census, the 2nd district stretched further north to the Wyoming border while losing the western portion of Eagle County.
2020s
Redistricting in 2021 moved Loveland back to the 4th district and Broomfield and western Jefferson County to the 7th district. Also the 3rd congressional district lost Jackson County, Routt County, and most of Eagle County to the 2nd district.
This district is anchored in Boulder and Larimer counties which have the bulk of population in the district: both counties are mainly anchored by the large college towns of Boulder and Fort Collins, providing Democratic strength in the district.
The other parts of the district are diverse, ranging from far western Denver suburbs to agricultural areas and mountain towns. Eagle and Summit counties, home to the ski resort towns of Vail and Breckenridge and other tourism dependent towns such as Avon, Frisco and Silverthorne, are Democratic strongholds: however Gilpin and Clear Creek counties, while also being tourism dependent and Democratic leaning, do not vote as strongly for the Democrats. Grand County leans Republican, though the ski resort areas of the county in Winter Park are heavily Democratic.
The suburban areas of Denver represented in the 2nd district are more competitive; while Broomfield itself leans Democratic, the Jefferson County foothills are historically a Republican stronghold, though urban sprawl is eroding Republican dominance in the area. Similarly, Larimer County outside of Fort Collins is heavily Republican, however the county leans Democratic due to the influence and population of Fort Collins.