"Building Less Housing Than People Demand Drives High Housing Costs. California is a desirable place to live. Yet not enough housing exists in the state’s major coastal communities to accommodate all of the households that want to live there. In these areas, community resistance to housing, environmental policies, lack of fiscal incentives for local governments to approve housing, and limited land constrains new housing construction. A shortage of housing along California’s coast means households wishing to live there compete for limited housing. This competition bids up home prices and rents. Some people who find California’s coast unaffordable turn instead to California’s inland communities, causing prices there to rise as well. In addition to a shortage of housing, high land and construction costs also play some role in high housing prices."
Land use policy is the cause, preventing supply to meet demand.
California’s High Housing Costs: Causes and Consequences
http://www.lao.ca.gov/reports/2015/finance/housing-costs/hou...
"Building Less Housing Than People Demand Drives High Housing Costs. California is a desirable place to live. Yet not enough housing exists in the state’s major coastal communities to accommodate all of the households that want to live there. In these areas, community resistance to housing, environmental policies, lack of fiscal incentives for local governments to approve housing, and limited land constrains new housing construction. A shortage of housing along California’s coast means households wishing to live there compete for limited housing. This competition bids up home prices and rents. Some people who find California’s coast unaffordable turn instead to California’s inland communities, causing prices there to rise as well. In addition to a shortage of housing, high land and construction costs also play some role in high housing prices."