As of January 8, 2025 it is represented by Judy Amabile.

[3] It was previously represented by Democrat Steve Fenberg, the former Senate President, since 2017.

[4] District 18 is based in the city of Boulder, also covering the outlying Boulder County communities of Lyons, Nederland, Gunbarrel, and Niwot.

It overlaps with the 10th, 11th, 12th, and 13th districts of the Colorado House of Representatives.

[7] Colorado state senators are elected to staggered four-year terms; under normal circumstances, the 18th district holds elections in presidential years.