WASHINGTON, Feb. 23 (Xinhua) -- Bachelor's degree attainment in the United States has topped 30 percent for the first time, the U. S. Census Bureau said Thursday.

According to a Census Bureau report, in March 2011, 30.4 percent of U.S. adults 25 and older had at least a bachelor's degree. As recently as 1998, fewer than one-quarter of people this age had this level of education.

"This is an important milestone in our history," Census Bureau Director Robert Groves said. "For many people, education is a sure path to a prosperous life. The more education people have the more likely they are to have a job and earn more money, particularly for individuals who hold a bachelor's degree."

People with a bachelor's degree had lower rates of unemployment than those with less education in every month from January 2008 to December 2010. This period included all but one month of the recent recession, which began in December 2007 and ended in June 2009.

According to the Census Bureau, the unemployment rate for high school dropouts reached a peak in February 2010 at 17.9 percent. In the same month, unemployment for people with a bachelor's degree was 5.9 percent.

Higher levels of educational attainment are associated with higher earnings. In 2009, the average monthly earnings for adults with a professional degree who worked full time were 11,927 dollars; the corresponding figure for bachelor's degree recipients was 5,455 dollars. Yet, one with lower levels of attainment may very well have higher earnings than those with higher levels, provided their degree is in a technical field. For instance, adults with an associate's degree in engineering earned an average of 4,800 per month, while bachelor's holders in education earned 3, 800.

According to the Census Bureau, more than one-third, or 20 million, of the nation's 56 million bachelor's degree holders held their degree in the broad field of science and engineering, including 4 million each in the social sciences and engineering and 3 million in biological, agricultural and environmental sciences.