Burnside is located at (35.755138, -109.630277).
According to the United States Census Bureau, the CDP has a total area of 9.3 square miles (24.1 km²), all land.
There were 173 households out of which 48.6% had children under the age of 18 living with them, 38.2% were married couples living together, 33.5% had a female householder with no husband present, and 22.0% were non-families. 21.4% of all households were made up of individuals and 3.5% had someone living alone who was 65 years of age or older. The average household size was 3.65 and the average family size was 4.35.
In the CDP the population was spread out with 44.8% under the age of 18, 10.0% from 18 to 24, 27.5% from 25 to 44, 13.6% from 45 to 64, and 4.1% who were 65 years of age or older. The median age was 21 years. For every 100 females there were 92.7 males. For every 100 females age 18 and over, there were 85.6 males.
The median income for a household in the CDP was $24,063, and the median income for a family was $25,441. Males had a median income of $18,661 versus $21,389 for females. The per capita income for the CDP was $8,236. About 30.6% of families and 38.9% of the population were below the poverty line, including 48.4% of those under age 18 and 13.2% of those age 65 or over.
The area is served by Ganado Primary School, Ganado Intermediate School, Ganado Middle School, and Ganado High School.