Caldwell added more people than any other Treasure Valley city last year.

New COMPASS population estimates, accepted April 27, 2026, put Caldwell’s gain at 5,160 residents between April 2025 and April 2026. Kuna added 4,810. Meridian added 4,730. Those three cities gained the most people in the region over that year, even though the percentage story still belongs to smaller towns on the edge.

Star is up 131% since the 2020 Census, the largest percentage increase in the COMPASS area. Kuna and Star each grew about 14% in a single year, compared with about 3% for Meridian and Nampa.

Ada and Canyon counties together are now estimated at 876,760 people, about 150,000 more than the 2020 Census. Add Boise and Elmore counties and the four-county total is 915,940, more than 20% growth since 2020.

For people moving to Idaho, that is the map in one snapshot: the west valley is still absorbing the most new residents, Meridian is still huge, and Star is the percentage rocket. COMPASS uses building permits, household size, vacancy, and annexations on top of the last Census count.

Stay tuned to Treasure Idaho for continued coverage of the numbers behind the move.

Project Quick Facts:

• Source: COMPASS 2026 population estimates (board accepted April 27, 2026; release April 29, 2026)
• Biggest numeric gains, April 2025-April 2026: Caldwell +5,160 – Kuna +4,810 – Meridian +4,730
• Star: +131% since 2020 Census
• Kuna and Star: about +14% in one year
• Ada + Canyon: 876,760 (+150,000 since 2020)
• Four counties (Ada, Canyon, Boise, Elmore): 915,940