At the turn of the century, under the Dawes Act, both Indian reservations were thrown open to homesteaders.

Unlike much of the rest of Utah Territory, settlement of the future Duchesne County area did not occur due to LDS Church pressures.

It was settled by individuals who obtained 160 acres under the federal Homestead Act.

The referendum passed, so Utah Governor William Spry proclaimed on January 4, 1915.

[5] Duchesne County's terrain is semi-arid, rough, and scarred with drainages.

[8] The northern part of the county contains much of the east–west oriented Uinta Mountains.

The highest natural point in Utah, Kings Peak at 13,528 feet (4,123 m), is located in Duchesne County.

Among non-Hispanic or Latino people, the racial makeup was 16,736 (85.4%) White, 21 (0.1%) African American, 875 (4.5%) Native American, 60 (0.3%) Asian, 39 (0.2%) Pacific Islander, 47 (0.2%) from other races, and 533 (2.7%) from two or more races.

There were 6,511 households in Duchesne County with an average size of 3.01 of which 4,937 (75.8%) were families and 1,574 (24.2%) were non-families.

As of the 2010 United States Census, there were 18,607 people, 6,003 households, and 4,703 families in the county.

In no national election since 1964 has the county selected the Democratic Party candidate (as of 2024).