[3] Part of the Fond du Lac Indian Reservation lies in northeastern Carlton County.

Carlton County is part of the Duluth, MN–WI Metropolitan Statistical Area.

The Saint Louis River flows east-southeast through the county, discharging into Lake Superior.

The Nemadji River and the South Fork Nemadji River flow east through the county, meeting a few miles east of its eastern boundary before reaching Lake Superior.

The county terrain consists of low rolling hills, heavily wooded,[4] and slopes to the several river valleys.

26.10% of all households were made up of individuals, and 12.00% had someone living alone who was 65 years of age or older.

[20] The Carlton County Board of Commissioners has five members, each representing one district.

[21] In April 2019 Lake and the Fond du Lac Police Department collaborated on sex trafficking training on behalf of other sheriff agencies that would be affected by the upcoming Enbridge Line 3.

[22] In 2017, Carlton County published a detailed Jail & Criminal Justice System Planning Study.

[24] The Democratic Party historically dominated the county, carrying it by wide margins in every presidential election from 1932 to 2012, but Donald Trump lost by only 300 votes in 2016 and 307 votes in 2020 (a margin of under 2% and holding the Democrats to only a plurality in both elections), signaling a new competitiveness in Carlton County.

This trend continued in 2024, with Donald Trump becoming the first Republican since Herbert Hoover in 1928 to win the county, receiving 50.13% of the vote.