Prior to redistricting the district was represented by Republicans Jim Smallwood and Mark Scheffel.

[3][4] District 4 is based in Douglas County on the southern outskirts of Denver, including Castle Pines, Castle Rock, Larkspur, Parker, Perry Park, The Pinery, and the southern tip of Aurora.

[6] Colorado state senators are elected to staggered four-year terms.

The old 4th district held elections in presidential years, but the new district drawn following the 2020 Census will hold elections in midterm years.

The 2022 election will be the first one held under the state's new district lines.