BOISE, Idaho — Growth in Ada and Canyon counties is showing no signs of slowing down.
The total population for both counties combined is estimated at 761,680 – an increase of just under 24,000 new residents from 2020, according to Community Planning Association of Southwest Idaho (COMPASS).
The COMPASS Board of Directors met Monday to accept the 2021 annual population estimates for Ada and Canyon counties.
At it is no surprise that the City of Meridian experienced the largest increase in population in the valley, growing by just over 8,500 in the past year.
COMPASS updates its population estimates as of April 1 each year using the most recent decennial Census count as the base. However, data from the 2020 decennial Census have not yet been released, because of delays due to the COVID-19 pandemic, so the 2021 estimates are based on 2010 Census data.
"We are eagerly anticipating the release of the 2020 Census data later this year," said COMPASS Principal Planner and demographer Carl Miller. "The decennial Census provides a once-in-a-decade opportunity to get full population counts and information about the characteristics of our communities."
Building from decennial Census counts, COMPASS updates the population estimates using local building construction permits, current household sizes and vacancy rates, and recent annexations (expansions of city limits).
Combined, that information not only allows COMPASS to estimate annual population growth, but also to reflect changes in how it is distributed among the cities and counties.
"While the region as a whole has experienced rapid growth year over year, the estimates are calculated based on locations for new residential construction and changes in local vacancy rates," Miller explained. "That way, we can tell what parts of the valley, and of each community, are growing fastest. Being able to track those changes on a local scale, as opposed to just broad regional growth, is important to addressing future needs."
The 2021 population estimates, including individual estimates for each city and both counties, can be found on the COMPASS website; follow link under "Hot Topics."
Here are the latest population estimates for the three largest cities:
Boise - 241,590
Meridian - 127,890
Nampa - 110,980
