The benchmark 10-year yield was down 3 basis points in morning trading at 1.5866pc.
James Barnes, director of fixed income at Bryn Mawr Trust, cited concerns about the coronavirus in China and a report that core U.S. retail sales were unchanged for January.
Traders also reduced risk in their portfolios heading into the weekend, wary of what news might emerge about the virus, similar to trading on previous Fridays. U.S. markets are closed on Monday for Presidents Day.
"Traders are more comfortable going into the weekend" with less risk, he said, adding that many believe "There's more risk to the downside than to the upside."
U.S. Commerce Department data showed U.S. consumer spending appeared to have slowed further in January, with sales at clothing stores declining by the most since 2009, which could raise concerns about the economy's ability to continue its moderate expansion.
Commerce said retail sales excluding automobiles, gasoline, building materials and food services were unchanged last month, weaker than the 0.3 percent ries economists had predicted in a Reuters poll. Data for December was revised down.
China's National Health Commission said it had recorded 121 new deaths and 5,090 new coronavirus cases on the mainland on Thursday, taking the total number of infected to 63,851. Some 55,748 people are being treated, while 1,380 have died of the virus.
Policymakers pledged to do more to stimulate economies hit by the virus, helping Asian stock markets edge higher.
The two-year U.S. Treasury yield, which typically moves in step with interest rate expectations, was down 2 basis points at 1.4217pc in morning trading.