NBC -- The federal government announced Thursday it will give community health centers $150 million to help hire more staff, buy equipment and rent space to treat more than a million new patients.

The grants are meant to help the health centers absorb some of the people expected to start seeking care — many for the first time — as they gain health insurance under the 2010 Affordable Care Act.

"This allows health centers to hire physicians, nurse practitioners, medical assistants to expand their capacity to be able to provide services to new patients," said Mary Wakefield, administration of the Health Resources and Services Administration (HRSA).

The cash will support 236 health centers across the country, Wakefield told reporters in a conference call, allowing them to add 1.25 million new patients.

There are about 1,200 federally qualified community health centers across the country. They started out as grassroots organizations, and in 1965, the federal government started giving them money when it became clear they were filling gaps in the messy U.S. health care system.

The Health and Human Services Department estimates they provide care now to 21 million people.

"Since the beginning of 2009, health centers have added 4 million patients and more than 35,000 new full-time positions," HRSA, which falls under HHS, said in a statement.

HHS looks to them not only to fill gaps in coverage, but as centers where people who need help the most can learn about the provisions of the Affordable Care Act that could make them eligible for heavily subsidized health insurance, or coverage under Medicaid.

Groups such as the Association of American Medical Colleges project a shortage of 90,000 medical doctors by 2020 as the population increases and ages — and as more people gain the ability to pay for treatment through new insurance marketplaces and expanded Medicaid programs.

"Health centers are key partners in the improving access to quality, affordable health care services for those who need it most. With new, affordable health insurance options available under the Affordable Care Act, community health centers are also key partners in helping uninsured residents sign up for health coverage — many of whom have been locked out of the health insurance market for years," HHS Secretary Kathleen Sebelius said in a statement.