Bluff is a census-designated place in San Juan County, Utah, United States. The population was 320 at the 2000 census. Bluff incorporated in 2018.
Bluff is located in the sparsely populated southeastern Utah canyonlands of the Colorado Plateau. The community is on the north margin of the San Juan River valley at the confluence of Cottonwood Wash with the San Juan. U.S. Route 191 and Utah State Route 163 pass through the community.
According to the United States Census Bureau, the town has a total area of 22.6 square miles (58.7 km²), of which, 22.1 square miles (57.2 km²) of it is land and 0.6 square miles (1.4 km²) of it (2.43%) is water.
As of the census of 2000, there were 320 people, 135 households, and 75 families residing in the town. The population density was 14.5 people per square mile (5.6/km²). There were 191 housing units at an average density of 8.6/sq mi (3.3/km²). The racial makeup of the town was 62.50% White, 35.00% Native American, 0.94% from other races, and 1.56% from two or more races. Hispanic or Latino of any race were 4.06% of the population.
There were 135 households out of which 28.9% had children under the age of 18 living with them, 47.4% were married couples living together, 5.9% had a female householder with no husband present, and 44.4% were non-families. 35.6% of all households were made up of individuals and 5.2% had someone living alone who was 65 years of age or older. The average household size was 2.37 and the average family size was 3.25.
In the town, the population was spread out with 25.9% under the age of 18, 8.8% from 18 to 24, 29.1% from 25 to 44, 25.6% from 45 to 64, and 10.6% who were 65 years of age or older. The median age was 38 years. For every 100 females, there were 102.5 males. For every 100 females age 18 and over, there were 104.3 males.
The median income for a household in the town was $23,906, and the median income for a family was $30,938. Males had a median income of $31,563 versus $14,792 for females. The per capita income for the CDP was $13,567. About 22.8% of families and 21.9% of the population were below the poverty line, including 27.7% of those under age 18 and 25.0% of those age 65 or over.