The report indicates that based on census data, 13.7 million people aged 19 to 29 had no health insurance, either public or private, in 2006, up from 13.3 million in 2005. Men and women in this age group accounted for 17 percent of the under-65 U.S. population, but made up almost 30 percent of the uninsured. At age 65, people enter the federal Medicare insurance program.
"There has been a steady upward climb in the number of young adults without health insurance coverage," Sara Collins, an author of the report, said in a telephone interview.
Reducing the number of Americans who lack health insurance has emerged as an issue in this year's U.S. presidential campaign. The government estimates that 47 million people have no health coverage in a country of about 300 million.
"If you ask young adults, as we do in our survey, if you've ever had problems accessing health care because of cost -- not filling a prescription, not seeing a specialist -- two thirds of uninsured young adults say yes," Collins said.
Hispanic and black young adults were at greater risk of being uninsured than whites, the report showed. While 23 percent of whites ages 19 to 29 lacked insurance, the figure was 36 percent of blacks and 53 percent of Hispanics.
Those aged 19 to 29 represent one of the largest and fastest-growing segments of the U.S. population lacking health insurance, the report said.