Civil Engineering in Star, Idaho.
Star is Ada County's fastest-growing city by percentage — up 58.8% since the 2020 census and growing at roughly 11% annually. Located between Eagle and Middleton along Highway 44, Star has a defining characteristic that no other Treasure Valley city shares: it is a dual-county city, with parcels in both Ada and Canyon counties under the same municipal government.
Ada County's fastest-growing city, with parcels in two counties.
Star is approximately 20,000 residents and growing at roughly 11% annually — the fastest growth rate of any major Ada County peer. 496 new residential subdivision lots were platted in 2025, more than Middleton (430) and roughly comparable to Nampa's active annexation market on a per-capita basis. This is one of the most active residential platting markets in Ada County.
The defining structural fact: in 2006, Star annexed approximately 650 acres from Canyon County. The Willowbrook Development annexation in 2018 (~1,550 acres) extended Star significantly northward into Canyon County, nearly doubling the city's acreage. About 800 of those acres are in the Purple Sage Road and Kingsbury Road corridor — in Canyon County. That dual-county status creates split school districts, split prosecutor arrangements, and jurisdiction complexities that affect every large annexation application.
The most important thing to know about Star.
The school district split
All of Star in Ada County is in the West Ada School District (Meridian Joint School District 2). Most of Star in Canyon County is in the Middleton School District 134, with portions in West Ada. The school your project feeds into depends on which county the parcel is in — and the Middleton School District is under capacity constraints.
Split county services
Ada County and Canyon County provide different services to different parts of Star. The city has separate prosecutorial contracts with both counties. Impact fee programs may differ by parcel location.
ACHD vs. ITD
Star's road network involves both ACHD (Ada County) and ITD (state highways, particularly SH-16/Highway 16). Large annexations near the SH-16 corridor require ITD coordination in addition to ACHD — a layer not present in most other Ada County cities.
Middleton's Ordinance 693
Middleton's school capacity ordinance blocks residential plats that push schools above 110% capacity. It applies only within Middleton city limits. But if your Star project in Canyon County feeds into the Middleton School District, you may face school capacity concerns at the public hearing even if the ordinance doesn't technically apply. Be prepared.
City Council, Planning & Zoning, and staff.
Mayor-council form with four at-large seats. Mayor Trevor Chadwick has emphasized sustainable growth and coordinated planning to mitigate sprawl.
City Council
Planning & Zoning Commission
Labels: CHAMPION ≥90% rezone approval rate · CAUTIOUS ≥75% · SWING ≥55% · SKEPTIC <55%
Planning Staff
Department: Planning & Zoning Department · URL: staridaho.org/pz. Star contracts law enforcement with the Ada County Sheriff's Office. The city uses both Ada County and Canyon County prosecutors for misdemeanor cases — a direct result of its dual-county status. For land use matters, Star's planning department is the primary contact.
Highway 16 expansion is the most significant infrastructure project affecting Star's growth trajectory.
ITD's plans for a Boise-area highway expansion have been a major topic in Star planning discussions, with price estimates approaching $1 billion. How and when SH-16 is improved directly affects the viability of large-scale development in northern Star and the Canyon County portions of the city.
The Willowbrook Development annexation (2018, ~1,550 acres) extended Star significantly northward into Canyon County. About 800 of those acres are in the Purple Sage Road and Kingsbury Road corridor — directly in the path of SH-16 expansion impact.
What this means for civil engineers: any large annexation in northern Star or the Canyon County portions of the city should track ITD project status as part of the pre-application due diligence. Coordinate with ITD in addition to ACHD. Verify access points, timing, and impact fees against current ITD planning at itd.idaho.gov.
City of Star links.
How to follow Star City Council.
Star archives City Council meetings on its YouTube channel; sort by most recent.
Watch on YouTubeStar FAQs.
- Is Star in Ada County or Canyon County?
- Both. Star's original city limits are in Ada County, but annexations starting in 2006 and expanding significantly in 2018 brought Canyon County land into the city. Your parcel's county determines which school district, which prosecutor, and which county services apply. Always verify through the Ada County Assessor or Star planning staff.
- Does Middleton's school capacity ordinance affect Star projects?
- Not directly — Ordinance 693 applies only within Middleton city limits. But if your Star project in Canyon County is in the Middleton School District's attendance area, expect school capacity questions at your public hearing. The distinction between 'the ordinance doesn't apply' and 'the school is still overcrowded' matters.
- Who is Star's mayor?
- Trevor Chadwick, in office since January 2020 and re-elected. He has emphasized sustainable growth and coordinated planning.
- Is Star growing faster than neighboring cities?
- Yes — at approximately 11% annually and 58.8% since 2020, Star is growing faster than Eagle, Kuna, or any other Ada County peer city by percentage. 496 new lots were platted in 2025.
- What road agencies are involved in Star applications?
- ACHD handles most local and collector roads. ITD is involved for projects near Highway 16 (SH-16) and other state routes. Both agencies must be coordinated for large annexations in northern Star.
- What is the Comprehensive Plan's growth direction for Star?
- Star's 2022 comp plan identifies northerly expansion toward Canyon County as the primary growth direction. The Purple Sage Road and Kingsbury Road corridor is specifically referenced. Applications in this area should align with the comp plan's future land use designations.
Built for a city in two counties.
Star's dual-county status, active annexation market, and SH-16 corridor complexity require engineering firms that can coordinate with both Ada and Canyon County agencies simultaneously. The 496 lots platted in 2025 represent a very active market — but applications in Canyon County portions of the city require a different pre-application checklist than Ada County portions. Bailey Engineering's experience across both Ada and Canyon County jurisdictions, including Canyon County annexation work in the Nampa corridor, provides the cross-county familiarity needed to navigate Star's unusual position as a city in two counties.