Narrowly beating a looming deadline, the Marin County Board of Supervisors last week approved a plan intended to ease a critical shortage of housing. The updated Housing Element identifies locations where at least 3,596 units can be developed in unincorporated Marin, with more than half set aside for low-income or medium-income housing.

The board’s approval was unanimous, and it ended an exhaustive and contentious process initiated in 2020 after the state ordered cities and counties…