In the Inland Empire, an economically depressed region in Southern California, President Obama’s health care law is expected to extend insurance coverage to more than 300,000 people by 2014. But coverage will not necessarily translate into care: Local health experts doubt there will be enough doctors to meet the area’s needs. There are not enough now.

Other places around the country, including the Mississippi Delta, Detroit and suburban Phoenix, face similar problems…

Moreover, across the country, fewer than half of primary care clinicians were accepting new Medicaid patients as of 2008, making it hard for the poor to find care even when they are eligible for Medicaid. The expansion of Medicaid accounts for more than one-third of the overall growth in coverage in President Obama’s health care law.