McAdoo's elevation is 1700 feet above sea level.
According to the United States Census Bureau, the borough has a total area of 0.3 square miles (0.9 km²), all of it land.
There were 1,034 households out of which 23.8% had children under the age of 18 living with them, 42.5% were married couples living together, 12.0% had a female householder with no husband present, and 40.3% were non-families. 37.1% of all households were made up of individuals and 20.9% had someone living alone who was 65 years of age or older. The average household size was 2.19 and the average family size was 2.89.
In the borough the population was spread out with 20.6% under the age of 18, 6.1% from 18 to 24, 28.4% from 25 to 44, 21.5% from 45 to 64, and 23.3% who were 65 years of age or older. The median age was 41 years. For every 100 females there were 91.1 males. For every 100 females age 18 and over, there were 87.0 males.
The median income for a household in the borough was $25,721, and the median income for a family was $31,625. Males had a median income of $28,281 versus $21,096 for females. The per capita income for the borough was $14,723. About 9.1% of families and 14.5% of the population were below the poverty line, including 24.7% of those under age 18 and 12.6% of those age 65 or over.