Location of Mackay in Custer County, Idaho.
MACKAY IDAHO Latitude and Longitude:
|• Total||0.87 sq mi (2.24 km2)|
|• Land||0.87 sq mi (2.24 km2)|
|• Water||0.00 sq mi (0.00 km2)|
|Elevation||5,906 ft (1,800 m)|
| • Estimate |
|• Density||550.81/sq mi (212.64/km2)|
|Time zone||UTC-7 ( Mountain (MST))|
|• Summer ( DST)||UTC-6 ( MDT)|
|GNIS feature ID||0397886|
|U.S. Decennial Census |
The climate of Mackay ranges from lows of -40 °F (-40 °C) to highs of +30 °F (-1 °C) in the winter. In the summer, temperatures range from lows of 30 °F (-1 °C) to highs of 100 °F (38 °C) in some areas. Mackay has a fairly dry climate, typical of high desert bordering alpine areas.
The main athletic attraction in the city is Mackay High School. The Miners have won ten state championships in football in the 1A (previously A-4) division and five state championships in basketball. Volleyball, girls' basketball and track are other athletic opportunities in Mackay.
As of the census  of 2010, there were 517 people, 247 households, and 137 families residing in the city. The population density was 601.2 inhabitants per square mile (232.1/km2). There were 352 housing units at an average density of 409.3 per square mile (158.0/km2). The racial makeup of the city was 98.8% White, 0.2% African American, 0.6% Native American, and 0.4% from two or more races. Hispanic or Latino of any race were 1.0% of the population.
There were 247 households of which 21.9% had children under the age of 18 living with them, 43.3% were married couples living together, 7.3% had a female householder with no husband present, 4.9% had a male householder with no wife present, and 44.5% were non-families. 39.7% of all households were made up of individuals and 23.9% had someone living alone who was 65 years of age or older. The average household size was 2.09 and the average family size was 2.72.
The median age in the city was 47.5 years. 21.5% of residents were under the age of 18; 5.1% were between the ages of 18 and 24; 19.3% were from 25 to 44; 31.4% were from 45 to 64; and 22.6% were 65 years of age or older. The gender makeup of the city was 51.6% male and 48.4% female.
As of the census  of 2000, there were 566 people, 261 households, and 149 families residing in the city. The population density was 651.8 people per square mile (251.2/km²). There were 353 housing units at an average density of 406.5 per square mile (156.7/km²). The racial makeup of the city was 98.59% White, 0.35% Native American, 0.71% from other races, and 0.35% from two or more races. Hispanic or Latino of any race were 2.30% of the population.
There were 261 households out of which 23.4% had children under the age of 18 living with them, 48.7% were married couples living together, 5.7% had a female householder with no husband present, and 42.9% were non-families. 39.5% of all households were made up of individuals and 21.1% had someone living alone who was 65 years of age or older. The average household size was 2.13 and the average family size was 2.86.
In the city, the population was spread out with 22.4% under the age of 18, 4.6% from 18 to 24, 23.9% from 25 to 44, 27.7% from 45 to 64, and 21.4% who were 65 years of age or older. The median age was 44 years. For every 100 females, there were 95.8 males. For every 100 females age 18 and over, there were 96.9 males.
The median income for a household in the city was $23,807, and the median income for a family was $31,667. Males had a median income of $38,750 versus $20,357 for females. The per capita income for the city was $14,237. About 13.0% of families and 18.4% of the population were below the poverty line, including 19.5% of those under age 18 and 19.8% of those age 65 or over.
On Friday, October 28, 1983, the Borah Peak earthquake occurred at 8:06 am MDT, measured at 6.9 on the moment magnitude scale. The Challis-Mackay region experienced rather thorough damage, with 11 commercial buildings and 39 homes with major damage; while another 200 houses were damaged, minor to moderately. Chickens were running all through the streets. Mackay in particular, about 50 miles (80 km) southeast of Challis, experienced the most severe damage. Most of the city's large buildings on its Main Street were damaged, to some extent; eight of these buildings were deemed condemned and closed down. Most of these buildings were built from materials such as brick, concrete block, and stone, each varying. 
- "2016 U.S. Gazetteer Files". United States Census Bureau. Retrieved Jul 26, 2017.
- "American FactFinder". United States Census Bureau. Retrieved 2012-12-18.
- "Population and Housing Unit Estimates". Retrieved June 9, 2017.
- "Census of Population and Housing". Census.gov. Retrieved June 4, 2015.
- "Profile of General Population and Housing Characteristics: 2010 Demographic Profile Data (DP-1): Mackay city, Idaho". U.S. Census Bureau, American Factfinder. Retrieved March 27, 2012.
- "US Gazetteer files: 2010, 2000, and 1990". United States Census Bureau. 2011-02-12. Retrieved 2011-04-23.
- U.S. Geological Survey Geographic Names Information System: Mackay, Idaho
- "US Gazetteer files 2010". United States Census Bureau. Archived from the original on 2012-01-24. Retrieved 2012-12-18.
- U.S. Geological Survey Geographic Names Information System: Borah Peak
- U.S. Geological Survey Geographic Names Information System: Mount McCaleb
- "American FactFinder". United States Census Bureau. Retrieved 2008-01-31.
- "Historic Earthquakes: Borah Peak, Idaho". USGS. 2008-07-16. Archived from the original on 2009-08-18. Retrieved 2010-03-30.