Idaho real estate glossary

Numeric vs. Percentage Population Growth: Ada and Canyon Counties

In the Treasure Valley, population expansion is measured two ways: through raw numeric increases and percentage growth rates. While Ada County consistently leads in total numeric volume due to its larger established population, smaller communities and Canyon County frequently experience higher percentage growth rates, reflecting rapid relative expansion compared to their existing size.

Updated with grounded research as of 2026-10-13.

The short answer

Numeric growth measures the raw number of new residents added to a population, whereas percentage growth measures the rate of change relative to the baseline population. In the Treasure Valley, Ada County reliably adds the largest volume of people, while smaller cities—such as Kuna and Star—often experience the most rapid percentage increases. Understanding both metrics is crucial for planning, as numeric growth impacts infrastructure demand, while percentage growth highlights how quickly the character and density of smaller communities are changing.

Key facts

Highest Numeric Growth (2025)
Ada County recorded the highest total numeric increase in Idaho in 2025, adding over 10,000 new residents.
Higher Percentage Growth (2025)
Canyon County recorded a 2.9% annual percentage growth rate, outpacing several other large urban counties in 2025.
Cumulative Growth (2020–2026)
Combined, Ada and Canyon counties grew by approximately 150,000 people in the six-year period following the 2020 Census.

Understanding Numeric Growth

Numeric growth represents the raw count of new residents. Because Ada County possesses a significantly larger population base, it consistently adds more people in absolute numbers than any other county in Idaho. This metric is vital for local planners who need to assess immediate demands on large-scale infrastructure, such as major highway expansions, water treatment capacity, and regional hospital systems.

The Significance of Percentage Growth

Percentage growth highlights the speed of expansion relative to a community's starting size. Smaller cities like Kuna and Star have seen percentage growth rates exceeding 14% year-over-year in certain reports. While the absolute number of people added in these towns is smaller than in Boise or Meridian, a high percentage growth rate indicates rapid changes to local demographics, neighborhood density, and school enrollment that can outpace existing services.

Methodology Behind the Data

Population estimates in the Treasure Valley are closely monitored by the Community Planning Association of Southwest Idaho (COMPASS). They analyze building permits, housing vacancy rates, and annexation records to provide up-to-date tracking of these trends. Relying on these local estimates rather than strictly decennial Census data allows for more responsive housing and planning decisions.

Common questions

Why do smaller cities sometimes show 'staggering' growth percentages?

When a city has a small starting population, adding only a few hundred new homes results in a large percentage increase. This is distinct from numeric growth, where larger cities like Boise add thousands of residents but show a smaller overall percentage change because the base population is so much larger.

Which metric should I prioritize for real estate decisions?

It depends on your goal. If you are looking for established infrastructure and larger service networks, consider areas with high numeric growth. If you are interested in up-and-coming areas where property values may be impacted by rapid development and increasing demand, high percentage growth areas often signal significant transformation.

Related Idaho questions

  • What is the projected population growth for Ada and Canyon counties by 2040?
  • How does COMPASS calculate population estimates for Treasure Valley cities?
  • Which cities in the Treasure Valley have the highest annual percentage growth rates?

Sources and verification