Concord Voters Face High-Stakes Open Space Measure In June

CONCORD, CA — The rules and borders that have shaped development in Contra Costa County for more than 35 years face renewal for only the second time since voters first approved them, with campaigns on both sides of Measure A ramping up ahead of the June 2 primary election.

Residents across Contra Costa County will vote on Measure A during in June, deciding whether to renew the county’s long-standing Urban Limit Line through 2051 — a boundary credited with protecting sweeping open space, ranchland, and scenic ridges from suburban sprawl for more than three decades.

The measure is headed for the ballot after the Contra Costa County Board of Supervisors voted in December 2025to place the proposal before voters in the June 2 primary election.

Supporters like the Greenbelt Alliance say Measure A would preserve the county’s rolling wildlands, agricultural valleys and fire-buffer zones while steering development toward existing cities and transit corridors.

Environmental groups including Save Mount Diablo and Greenbelt Alliance argue the boundary has helped stop unchecked development since voters first approved it in 1990.

Opponents counter that extending the limit line could worsen the region’s housing affordability crisis by restricting future land available for development.

The debate has turned Measure A into one of the Bay Area’s sharpest political clashes between conservation advocates and housing activists.

The Yes on Measure A campaign is being driven primarily by environmental organizations and smart-growth advocates, led publicly by Save Mount Diablo and backed by groups including Greenbelt Alliance, East Bay for Everyone, and regional conservation groups.

Opposition is tied most visibly to the Contra Costa Taxpayers Association, property-rights advocates, and some development interests arguing the measure would tighten housing supply and raise prices, according to reports.

What is notable is that, as of mid-May 2026, no massive developer cash flood has been publicly reported in the way California land-use fights sometimes attract millions from real-estate PACs. Instead, the battle has to date centered more on messaging, endorsements and coalition-building. That tension is why Measure A has become one of the Bay Area’s most closely watched land-use votes of 2026.