The March rate was up from a revised 10.9 percent rate in February and well above the national rate of 8.5 percent. The previous state record was set in January 1983.
Allendale County continued to have the highest unemployment rate at 22.3 percent, but that was down one percentage point from March. Three other counties Marion, Chester and Union had rates of 20 percent or above.
South Carolina had the nation's second highest unemployment rate for the first two months of this year behind Michigan, but not all state figures for March have been released yet. Still, the state remains behind at least Michigan at 12.6 percent in March and Oregon with 12.1.
The number of unemployed workers in South Carolina rose by about 10,000 to around 248,600, according to the commission.
There was some good news in Friday's report: The number of jobs in hospitality and leisure as well as health and education increased in March. That was offset by continuing declines in construction and agricultural jobs, the commission said.
The number of people working or looking for a job in South Carolina also dropped by about 4,000 people to 2,185,500.
Lexington County had the lowest rate at 7.9 percent.
South Carolina's unemployment rate was 5.7 percent in February 2008 when the 13 months of increases began.