A new report estimates about half of immigrants living without legal documentation in California, 1.4 million, would qualify for Medi-Cal, if the program were open to them. It also provides rare data about where they live.

The Public Policy Institute of California’s report divides immigrants without legal documentation by region. As lawmakers consider opening Medi-Cal to those immigrants, researcher Shannon McConville says the data could help local planning.

“Health care delivery and also insurance markets are really organized at a regional level,” McConville says.

The report finds more than a third of that population lives in Los Angeles County, 60 percent of whom would qualify for Medi-Cal. That’s a lot to add to the region’s system, but McConville says it could also prevent expensive hospital visits.

“The idea is that if uninsured have access to comprehensive health coverage, then hopefully they are able to receive preventative care,” says McConville.

A state fiscal analysis this year found this expansion of Medi-Cal coverage could cost $900 million.