The unemployment rate dropped to 5.8% in March from 6.1% in February, the Labor Department said on Friday.
The labor force participation rate rose to 69.4%, from 67.4% in January, it said.
The economy expanded at a 2.2% annual rate in the three months through March, the lowest since October 2008.
The jobless rate dropped by 0.3 percentage point to 5% from 5.4%.
It was the weakest reading since February 2011, when the rate was 6.2%.
The labor force increased by 568,000 people in March, a sign of strength after the government revised down its forecast for employment to 3.4 million.
The U.S. is set to report its final monthly employment numbers later this week.
