Products, Services, and Data

Demographics: Current and Historical Population Estimates

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

Since 1990, COMPASS has used a housing unit method estimation model 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 reflect changes in population. It is broken into three distinct parts: housing unit estimation, household population estimation, and city assignment.

To arrive at a housing unit estimate, COMPASS adds the number of new residential permits—using data provided by local cities and counties—to the latest decennial census counts. It then incorporates occupancy rate information from Idaho Power to arrive at a household (i.e., occupied housing units) population estimate. Group quarters, or places where people live or stay in a group living arrangement such as dormitories or prisons, are kept static from decennial counts. These population estimates are assigned to cities based on the most current city limit boundaries.

The calculation COMPASS uses to build population estimates is as follows:

Population = [(h + r) * s * o)] + q
where
h = decennial census households
r = new residential units permitted
s = household size
o = residential occupancy rate
q = group quarters population

Additional information about COMPASS population estimates is available at www.compassidaho.org/documents/prodserv/demo/PopulationEstimateMethodology2016.pdf.
COMPASS estimates are based on building permit information through December 31 of each year and are estimated for April 1 of each year. More information about building permits is available in the annual Development Monitoring Report.

Due to the difference in time of estimates, as well as the methodology used to prepare the estimates, discrepancies will occur between the COMPASS and Census estimates. Learn more about differences between COMPASS and US Census Bureau methodologies.

2010-2017 Population Estimates by City Limit Boundaries 
(Updated 4/1/2017)

COMPASS uses Idaho Department of Labor data, including firms’ locations, industry sector types, and number of employees, to develop annual regional employment estimates.

For more information contact: Carl Miller, 208/475-2239.