(CNN) - A new survey indicates 15.6% of Americans don't have health insurance, marking the lowest rate since 2008.
The poll comes as good news for the White House, a week after it announced more than 7 million people had signed up on the federal and state exchanges for health care insurance.
The health care law also includes expanded Medicaid insurance for the poor in many states, but those participants are not part of the sign-up total.
For the health care law to work successfully, the Obama administration needs a significant portion of enrollees to be young. According to Gallup, "the uninsured rate dropped by about the same amount among adults aged 26 to 64 as it did among those aged 18-25."
The rate fell across every major demographic group, but it dropped the most for lower-income Americans and African-Americans.
Gallup interviewed 43,562 adults by telephone from January 2 to March 31. The survey's overall sampling error is plus or minus one percentage point.
CNN's Ashley Killough contributed to this report.