The Centers for Disease Control and Prevention plans to offer rapid HIV tests at drugstores in 24 cities and rural communities.
The test involves a swab of the inside of the mouth, and the results are ready in about 20 minutes.
The CDC is already offering the free tests in seven drugstores and plans to expand to more locations this summer.
The U.S. government is spending $1.2 million on the project.
Health officials estimate that more than 1 million Americans are infected with HIV, but as many as 20 percent of them do not know they carry the virus.
For more information, visit www.cdc.gov/hiv/