Theoretically, the new city could have a population of several hundred thousand people. Plans call for it to rise on 18,000 acres just west of Rio Vista, a town of about 10,000 people on the Sacramento River. The city would be separated from Rio Vista by 712 acres of parkland, sports facilities and open space.

But that is a long way off. If the ballot measure is approved, other government approvals would then be required. Environmental groups have signaled lawsuits are possible, which could tie up the matter in court. The soonest construction could begin is 2026.