Products, Services, and Data

Demographics: Current and Historical Population Estimates

COMPASS develops annual population estimates for city and county jurisdictions in Ada and Canyon Counties.

These estimates are used as indicators of economic conditions and for planning various government programs, evaluating land development impacts on the transportation network, and establishing COMPASS member dues.



COMPASS uses a housing unit method to update population estimates at the city and county level. This method is based on the premise that changes in the number of occupied housing units reflects changes in population.

COMPASS calculates this using the following formula:

Population = [(h + r) * s * o)] + q

h = decennial census households

  • The number of households counted in the most recent decennial census.

r = new residential units permitted

  • The number of new residential housing permits issued since the latest decennial census year. Data are provided by the cities and counties and are as of December 31 of the previous year.

s = household size

  • The average number of persons in a household, based on type (e.g., single-family vs. multi-family) and location, as different communities have different average household sizes. These data are derived from the US Census Bureau’s American Community Survey.

o = residential occupancy rate

  • Based on occupancy rate information from Idaho Power.

q = group quarters population

  • Group quarters are places where people live or stay in a group living arrangement such as dormitories or prisons; these populations are updated with each decennial census, then kept static until the next decennial census.

Once calculated, population estimates are assigned to cities based on the most current city limit boundaries.


Learn more

Development Monitoring Reports (new residential units permitted)

Detailed Population Estimate Methodology

For more information contact: Liisa Itkonen, 208/475-2241.